{"id":186,"date":"2022-06-03T06:57:38","date_gmt":"2022-06-03T06:57:38","guid":{"rendered":"https:\/\/www.testleaf.com\/blog\/?p=186"},"modified":"2026-03-06T14:22:48","modified_gmt":"2026-03-06T08:52:48","slug":"step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview","status":"publish","type":"post","link":"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/","title":{"rendered":"Step by Step Approach to Solve Any Programming Questions in your QA Interview"},"content":{"rendered":"<div style=\"margin-top: 0px; margin-bottom: 0px;\" class=\"sharethis-inline-share-buttons\" ><\/div><!--[if lt IE 9]><script>document.createElement('audio');<\/script><![endif]-->\n<audio class=\"wp-audio-shortcode\" id=\"audio-186-1\" preload=\"none\" style=\"width: 100%;\" controls=\"controls\"><source type=\"audio\/mpeg\" src=\"https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2022\/06\/Step-by-Step-Approach-to-Solve-Any-Programming-Questions-in-your-QA-Interview.mp3?_=1\" \/><a href=\"https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2022\/06\/Step-by-Step-Approach-to-Solve-Any-Programming-Questions-in-your-QA-Interview.mp3\">https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2022\/06\/Step-by-Step-Approach-to-Solve-Any-Programming-Questions-in-your-QA-Interview.mp3<\/a><\/audio>\n<p>&nbsp;<\/p>\n<p>This article is based on my recent 100+ real live interview experiences with my SDET learners with many product organizations in India.<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Skill_up_before_you_apply\" >Skill up before you apply<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_1_Understand_the_Problem\" >Step 1: Understand the Problem<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_2_Build_your_test_data_set\" >Step 2: Build your test data set<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_3_Take_a_moment_to_think_through_solutions\" >Step 3: Take a moment to think through solutions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_4_Ask_for_hints\" >Step 4: Ask for hints<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_5_Always_start_with_brute-force\" >Step 5: Always start with brute-force<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_6_Write_Psuedo_Code_first\" >Step 6: Write Psuedo Code first<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_7_Write_your_clean_code\" >Step 7: Write your clean code<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_8_Debug_your_code_with_test_data\" >Step 8: Debug your code with test data<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_9_Run_for_all_test_data\" >Step 9: Run for all test data<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Step_10_Ask_for_feedback\" >Step 10: Ask for feedback.<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#Worked_Example_Apply_the_10_Steps_to_One_Problem_Beginner-Friendly\" >Worked Example: Apply the 10 Steps to One Problem (Beginner-Friendly)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/#FAQs\" >FAQs\u00a0<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"Skill_up_before_you_apply\"><\/span><strong>Skill up before you apply <\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<div>Suppose you are looking to <a href=\"https:\/\/www.testleaf.com\/blog\/sdet-role-responsibilities-and-salary-comparison-india-vs-abroad-2025-guide\/\">become a high paid SDET<\/a>. In that case, I recommend you to start solving 100\u2013150 easy\/medium DSA problems in Leetcode with a brute force approach and optimize using other algorithms.<br \/>\nMost interviewers watch out for your approach to solving problems, not the solution itself. The below 10 Steps can guide you to crack your QA coding round.<\/div>\n<div><\/div>\n<div>To solve programming questions in QA interviews, clarify inputs\/outputs\/constraints, build test data first, start with a brute-force approach, then optimize with complexity. Write pseudo code, implement clean code, debug with your test data, and explain trade-offs clearly. Interviewers score your reasoning and communication as much as correctness.<\/div>\n<div><\/div>\n<div>\n<h3 data-start=\"2849\" data-end=\"2866\"><strong data-start=\"2849\" data-end=\"2866\">Key Takeaways<\/strong><\/h3>\n<ul data-start=\"2867\" data-end=\"3187\">\n<li data-start=\"2867\" data-end=\"2972\">\n<p data-start=\"2869\" data-end=\"2972\">Ask clarifying questions + confirm constraints before coding.<\/p>\n<\/li>\n<li data-start=\"2973\" data-end=\"3081\">\n<p data-start=\"2975\" data-end=\"3081\">Use test data to drive your approach (positive, edge, negative).<\/p>\n<\/li>\n<li data-start=\"3082\" data-end=\"3187\">\n<p data-start=\"3084\" data-end=\"3187\">Start brute force \u2192 then optimize with time\/space complexity.<\/p>\n<\/li>\n<\/ul>\n<p>Many product-company rounds in India expect you to communicate clearly in remote screenshare interviews\u2014so narrate your thinking, write pseudo code first, and validate assumptions early.<\/p>\n<\/div>\n<div><\/div>\n<h2><span class=\"ez-toc-section\" id=\"Step_1_Understand_the_Problem\"><\/span><strong>Step 1: Understand the Problem<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<div>\n<p>During the interview, most of us become nervous\u00a0during on coding round and do not read the question thoroughly, especially in case of word problems. By chance, if you did not understand the question (that happened a few times for our learners during the mocks\/real with difficult question), ask the interviewer to detail the question with example(s).Here are a few follow-up questions either to ask yourself or to the interviewer:<\/p>\n<ul>\n<li>What is\/are the input(s) given to the problem?<\/li>\n<li>What is the expected output data type?<\/li>\n<li>Do I have constraints to solve this problem?<\/li>\n<li>How big the test data set could be?<\/li>\n<\/ul>\n<\/div>\n<div>\n<p><strong><b>Pro Tip:<\/b><\/strong>\u00a0It is essential to ask the right questions like what-if cases and edge cases early to the interviewer, and it will help design your tests well.<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_2_Build_your_test_data_set\"><\/span><strong>Step 2: Build your test data set<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>It is time to show up your QA testing skills. Recommend to build a minimum of 3 test data sets, including \u2014 Positive, Edge, Negative, and edge data set, is the most preferred ask by most interviewers. Convert the test data into unit tests and can be used for test-driven development (TDD).<br \/>\n<strong><b>Pro Tip:<\/b><\/strong>\u00a0Once you scribe them, validate with the interviewer if the test data set covers the expectations are not!<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_3_Take_a_moment_to_think_through_solutions\"><\/span><strong>Step 3: Take a moment to think through solutions<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Considering you have solved many LC problems, you mostly would get a (similar) situation that you may have cracked. But, do not show up quickly to interviewers else. You would get another question (it happened twice in 100+ interviews in the last few months). So, take a few moments to think through the problem-solution \/ workaround with the given data &amp; constraints.<br \/>\n<strong>Pro Tip:\u00a0<\/strong>It is important to constantly communicate to the interviewer (especially when you are taking an online interview), even when thinking about the solution(s)!<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_4_Ask_for_hints\"><\/span><strong>Step 4: Ask for hints<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>What if you cannot think of any solution? I recommended all my learners ask the interviewers shamelessly for hints\/help. It worked most of the time, as many interviewers were willing to help you.<br \/>\n<strong><b>Pro Tip:<\/b><\/strong>\u00a0When you get a hint from the interviewer, it is essential to thank them for the help. It helps to show your attitude.<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_5_Always_start_with_brute-force\"><\/span><strong>Step 5: Always start with brute-force<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Though you know multiple and optimized solutions, it is always recommended to start with the brute-force approach unless the interviewer defines the problem constraint. If there is a time challenge, mention the brute-force approach and its O-Notations.<br \/>\n<strong><b>Pro Tip:<\/b><\/strong>\u00a0It is essential to communicate the time and space complexity for every solution, especially from the testing side.<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_6_Write_Psuedo_Code_first\"><\/span><strong>Step 6: Write Psuedo Code first<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Most of the live coding rounds are about 45 to 60 minutes long. Generally, you get about 1\u20132 coding questions and may be other questions including\u00a0front\/back end automation and a few other questions like agile and test data enumerations. With that said, each programming question may be about 15\u201320 minutes on average.<br \/>\nSometimes, you may get lost when complex coding problems. It is always a good idea to scribe the psuedo code first and get confirmation from the interview before you code.<br \/>\n<strong><b>Pro Tip:<\/b><\/strong>\u00a0Validate the psuedo code with the interviewer, and many times, they will be happy to advise a few corrections before you code.<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_7_Write_your_clean_code\"><\/span><strong>Step 7: Write your clean code<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Apply clean coding practices when you code your solution. It begins with your method\/variable naming conventions and meaningful short comments to use appropriate (built-in) methods for the solution. It is good to confirm with the interviewer when you are about to use the built-in methods as many of them say \u2018NO\u2019 to them.<br \/>\n<strong><b>Pro Tip:\u00a0<\/b><\/strong>Always practice your coding with a text editor. And many interviewers may use code sharing platforms, and they may not have auto-complete options.<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_8_Debug_your_code_with_test_data\"><\/span><strong>Step 8: Debug your code with test data<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>As a test engineer, you may wish to run the test and not be keen on debugging. That may be the greatest mistake. Hence, recommended starting with debugging every line of code, step into\/over and walk through the interviewer. Remember to communicate O Notations for every solution that you built.<br \/>\n<strong><b>Pro Tip:<\/b><\/strong>\u00a0Ask the interviewer if they like to run for specific test data. Often, your coded solution can be new to the interviewer, and they may be interested in knowing if their test data works against your code.<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_9_Run_for_all_test_data\"><\/span><strong>Step 9: Run for all test data<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>If all the above steps went well, take a deep breath and run your code against all test data you built in step 2. If one or more fails, start debugging with the consent of the interviewer.<br \/>\n<strong><b>Pro Tip:<\/b><\/strong>\u00a0Make sure unit tests have proper assertions against the expected and actual. That would help you to test faster.<\/p>\n<\/div>\n<div>\n<h2><span class=\"ez-toc-section\" id=\"Step_10_Ask_for_feedback\"><\/span><strong>Step 10: Ask for feedback.<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Hurray, you are on the final step. It\u2019s time for you to ask for feedback from the coding test and note them on your sticky notes. If improvements are mentioned during the interview, say that you will begin working on them swiftly today.<\/p>\n<h2 data-start=\"0\" data-end=\"72\"><\/h2>\n<h2 data-start=\"0\" data-end=\"72\"><span class=\"ez-toc-section\" id=\"Worked_Example_Apply_the_10_Steps_to_One_Problem_Beginner-Friendly\"><\/span><strong>Worked Example: Apply the 10 Steps to One Problem (Beginner-Friendly)<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3 data-start=\"74\" data-end=\"108\"><strong>Problem (classic QA interview)<\/strong><\/h3>\n<p data-start=\"109\" data-end=\"238\"><strong data-start=\"109\" data-end=\"164\">Find the first non-repeating character in a string.<\/strong><br data-start=\"164\" data-end=\"167\" \/>Example: <code data-start=\"176\" data-end=\"185\">\"swiss\"<\/code> \u2192 <strong data-start=\"188\" data-end=\"197\"><code data-start=\"190\" data-end=\"195\">\"w\"<\/code><\/strong> (because <code data-start=\"207\" data-end=\"210\">s<\/code> repeats, <code data-start=\"220\" data-end=\"223\">w<\/code> appears once).<\/p>\n<h3 data-start=\"245\" data-end=\"282\"><strong>1) Inputs \/ Outputs \/ Constraints<\/strong><\/h3>\n<p data-start=\"283\" data-end=\"438\"><strong data-start=\"283\" data-end=\"293\">Input:<\/strong> A string <code data-start=\"303\" data-end=\"306\">s<\/code><br data-start=\"306\" data-end=\"309\" \/><strong data-start=\"309\" data-end=\"320\">Output:<\/strong> The first character that occurs only once. If none exist, return <code data-start=\"386\" data-end=\"390\">-1<\/code> (or empty).<br data-start=\"402\" data-end=\"405\" \/><strong data-start=\"405\" data-end=\"438\">Constraints (assume typical):<\/strong><\/p>\n<ul data-start=\"439\" data-end=\"571\">\n<li data-start=\"439\" data-end=\"460\">\n<p data-start=\"441\" data-end=\"460\"><code data-start=\"441\" data-end=\"460\">0 \u2264 len(s) \u2264 10^5<\/code><\/p>\n<\/li>\n<li data-start=\"461\" data-end=\"509\">\n<p data-start=\"463\" data-end=\"509\">Case-sensitive (treat <code data-start=\"485\" data-end=\"488\">A<\/code> and <code data-start=\"493\" data-end=\"496\">a<\/code> differently)<\/p>\n<\/li>\n<li data-start=\"510\" data-end=\"571\">\n<p data-start=\"512\" data-end=\"571\">String may include spaces or symbols (handle as characters)<\/p>\n<\/li>\n<\/ul>\n<h3 data-start=\"578\" data-end=\"606\"><strong>2) Test data (3\u20135 cases)<\/strong><\/h3>\n<div class=\"TyagGW_tableContainer\">\n<div class=\"group TyagGW_tableWrapper flex flex-col-reverse w-fit\" tabindex=\"-1\">\n<table class=\"w-fit min-w-(--thread-content-width)\" data-start=\"607\" data-end=\"896\">\n<thead data-start=\"607\" data-end=\"652\">\n<tr data-start=\"607\" data-end=\"652\">\n<th class=\"\" data-start=\"607\" data-end=\"619\" data-col-size=\"sm\">Test Case<\/th>\n<th class=\"\" data-start=\"619\" data-end=\"627\" data-col-size=\"sm\">Input<\/th>\n<th class=\"\" data-start=\"627\" data-end=\"645\" data-col-size=\"sm\">Expected Output<\/th>\n<th class=\"\" data-start=\"645\" data-end=\"652\" data-col-size=\"sm\">Why<\/th>\n<\/tr>\n<\/thead>\n<tbody data-start=\"671\" data-end=\"896\">\n<tr data-start=\"671\" data-end=\"721\">\n<td data-start=\"671\" data-end=\"675\" data-col-size=\"sm\">1<\/td>\n<td data-start=\"675\" data-end=\"687\" data-col-size=\"sm\"><code data-start=\"677\" data-end=\"686\">\"swiss\"<\/code><\/td>\n<td data-start=\"687\" data-end=\"695\" data-col-size=\"sm\"><code data-start=\"689\" data-end=\"694\">\"w\"<\/code><\/td>\n<td data-start=\"695\" data-end=\"721\" data-col-size=\"sm\">First unique character<\/td>\n<\/tr>\n<tr data-start=\"722\" data-end=\"769\">\n<td data-start=\"722\" data-end=\"726\" data-col-size=\"sm\">2<\/td>\n<td data-start=\"726\" data-end=\"739\" data-col-size=\"sm\"><code data-start=\"728\" data-end=\"738\">\"aabbcc\"<\/code><\/td>\n<td data-start=\"739\" data-end=\"746\" data-col-size=\"sm\"><code data-start=\"741\" data-end=\"745\">-1<\/code><\/td>\n<td data-start=\"746\" data-end=\"769\" data-col-size=\"sm\">No unique character<\/td>\n<\/tr>\n<tr data-start=\"770\" data-end=\"813\">\n<td data-start=\"770\" data-end=\"774\" data-col-size=\"sm\">3<\/td>\n<td data-start=\"774\" data-end=\"784\" data-col-size=\"sm\"><code data-start=\"776\" data-end=\"783\">\"aab\"<\/code><\/td>\n<td data-start=\"784\" data-end=\"792\" data-col-size=\"sm\"><code data-start=\"786\" data-end=\"791\">\"b\"<\/code><\/td>\n<td data-start=\"792\" data-end=\"813\" data-col-size=\"sm\">Unique at the end<\/td>\n<\/tr>\n<tr data-start=\"814\" data-end=\"847\">\n<td data-start=\"814\" data-end=\"818\" data-col-size=\"sm\">4<\/td>\n<td data-start=\"818\" data-end=\"825\" data-col-size=\"sm\"><code data-start=\"820\" data-end=\"824\">\"\"<\/code><\/td>\n<td data-start=\"825\" data-end=\"832\" data-col-size=\"sm\"><code data-start=\"827\" data-end=\"831\">-1<\/code><\/td>\n<td data-start=\"832\" data-end=\"847\" data-col-size=\"sm\">Empty input<\/td>\n<\/tr>\n<tr data-start=\"848\" data-end=\"896\">\n<td data-start=\"848\" data-end=\"852\" data-col-size=\"sm\">5<\/td>\n<td data-start=\"852\" data-end=\"864\" data-col-size=\"sm\"><code data-start=\"854\" data-end=\"863\">\"AabbA\"<\/code><\/td>\n<td data-start=\"864\" data-end=\"872\" data-col-size=\"sm\"><code data-start=\"866\" data-end=\"871\">\"a\"<\/code><\/td>\n<td data-start=\"872\" data-end=\"896\" data-col-size=\"sm\">Case-sensitive check<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<p data-start=\"898\" data-end=\"988\"><em data-start=\"898\" data-end=\"988\">(You can say this in the interview: \u201cI\u2019ll validate positive, negative, and edge cases.\u201d)<\/em><\/p>\n<h3 data-start=\"995\" data-end=\"1031\"><strong>3) Brute force idea + complexity<\/strong><\/h3>\n<p data-start=\"1032\" data-end=\"1219\"><strong data-start=\"1032\" data-end=\"1041\">Idea:<\/strong> For each character, scan the whole string and count occurrences. Return the first with count = 1.<br data-start=\"1139\" data-end=\"1142\" \/><strong data-start=\"1142\" data-end=\"1162\">Time complexity:<\/strong> <code data-start=\"1163\" data-end=\"1171\">O(n^2)<\/code><br data-start=\"1171\" data-end=\"1174\" \/><strong data-start=\"1174\" data-end=\"1195\">Space complexity:<\/strong> <code data-start=\"1196\" data-end=\"1202\">O(1)<\/code> (ignoring input)<\/p>\n<p data-start=\"1221\" data-end=\"1286\"><strong data-start=\"1221\" data-end=\"1240\">Why mention it:<\/strong> It shows you can start simple, then optimize.<\/p>\n<h3 data-start=\"1293\" data-end=\"1327\"><strong>4) Optimized idea + complexity<\/strong><\/h3>\n<p data-start=\"1328\" data-end=\"1384\"><strong data-start=\"1328\" data-end=\"1337\">Idea:<\/strong> Use a frequency map (hash map \/ dictionary).<\/p>\n<ul data-start=\"1385\" data-end=\"1480\">\n<li data-start=\"1385\" data-end=\"1421\">\n<p data-start=\"1387\" data-end=\"1421\">First pass: count each character<\/p>\n<\/li>\n<li data-start=\"1422\" data-end=\"1480\">\n<p data-start=\"1424\" data-end=\"1480\">Second pass: return the first character with count = 1<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"1482\" data-end=\"1576\"><strong data-start=\"1482\" data-end=\"1502\">Time complexity:<\/strong> <code data-start=\"1503\" data-end=\"1509\">O(n)<\/code><br data-start=\"1509\" data-end=\"1512\" \/><strong data-start=\"1512\" data-end=\"1533\">Space complexity:<\/strong> <code data-start=\"1534\" data-end=\"1540\">O(k)<\/code> where <code data-start=\"1547\" data-end=\"1550\">k<\/code> is number of unique chars<\/p>\n<p data-start=\"1578\" data-end=\"1650\"><strong data-start=\"1578\" data-end=\"1596\">Why this wins:<\/strong> Works fast for large inputs and is simple to explain.<\/p>\n<h3 data-start=\"1657\" data-end=\"1690\"><strong>5) Clean code (short snippet)<\/strong><\/h3>\n<p data-start=\"1691\" data-end=\"1728\">Java (interview-friendly, clean):<\/p>\n<div class=\"contain-inline-size rounded-2xl corner-superellipse\/1.1 relative bg-token-sidebar-surface-primary\">\n<div class=\"sticky top-[calc(var(--sticky-padding-top)+9*var(--spacing))]\">\n<div class=\"absolute end-0 bottom-0 flex h-9 items-center pe-2\">\n<div class=\"bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs\">\n<pre>import java.util.*;\r\n\r\npublic class FirstUniqueChar {\r\npublic static char firstNonRepeatingChar(String s) {\r\nif (s == null || s.isEmpty()) return '\\0'; \/\/ use '\\0' as \"not found\"\r\n\r\nMap&lt;Character, Integer&gt; freq = new LinkedHashMap&lt;&gt;();\r\nfor (char c : s.toCharArray()) {\r\nfreq.put(c, freq.getOrDefault(c, 0) + 1);\r\n}\r\n\r\nfor (Map.Entry&lt;Character, Integer&gt; entry : freq.entrySet()) {\r\nif (entry.getValue() == 1) return entry.getKey();\r\n}\r\n\r\nreturn '\\0';\r\n}\r\n\r\npublic static void main(String[] args) {\r\nSystem.out.println(firstNonRepeatingChar(\"swiss\")); \/\/ w\r\nSystem.out.println(firstNonRepeatingChar(\"aabbcc\")); \/\/ \\0\r\n}\r\n}<\/pre>\n<p><span style=\"font-size: 16px;\"><strong data-start=\"2454\" data-end=\"2493\">If you want to return <code data-start=\"2478\" data-end=\"2482\">-1<\/code> instead:<\/strong> return an index instead of char (or return <code data-start=\"2537\" data-end=\"2559\">String.valueOf(char)<\/code> and return <code data-start=\"2571\" data-end=\"2577\">\"-1\"<\/code> when not found).<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<h3><\/h3>\n<h3><strong>Final Thoughts<\/strong><\/h3>\n<p>Thank you for reading this article, and I will be honoured by your claps and shares. At\u00a0<a href=\"https:\/\/www.testleaf.com\/?utm_source=blog_post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><u>TestLeaf<\/u><\/a>, we assisted 10000+ manual testers in transforming their career towards test automation engineering with the help of <a href=\"https:\/\/www.testleaf.com\/?utm_source=blog_post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><u>automation testing courses<\/u><\/a> (Grow Vertically), development (Shift-Left) and DevOps (Shift Right). like to know about <a href=\"https:\/\/www.testleaf.com\/?utm_source=blog_post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\">software testing course<\/a> learn from Testleaf.<\/p>\n<\/div>\n<h2 data-start=\"4750\" data-end=\"4796\"><span class=\"ez-toc-section\" id=\"FAQs\"><\/span><strong>FAQs\u00a0<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\t<div class=\"tlfaq\" id=\"tlfaq-ee5e4958-ef01-40d6-8f4f-b38af9c6a1e3\"\n\t     data-single-open=\"1\">\n\t\t\n\t\t<div class=\"tlfaq__items\" role=\"region\" aria-label=\"FAQ\">\n\t\t\t\t\t\t\t<details class=\"tlfaq__item\" open id=\"tlfaq-ee5e4958-ef01-40d6-8f4f-b38af9c6a1e3-0\">\n\t\t\t\t\t<summary class=\"tlfaq__question\">\n\t\t\t\t\t\t<span class=\"tlfaq__qtext\">How do I approach coding questions in a QA interview?<\/span>\n\t\t\t\t\t\t<span class=\"tlfaq__icon\" aria-hidden=\"true\"><\/span>\n\t\t\t\t\t<\/summary>\n\t\t\t\t\t<div class=\"tlfaq__answer\">\n\t\t\t\t\t\tUse a test-first mindset by first clarifying the requirements, identifying test data, proposing a brute-force solution, and then improving it while explaining the logic and complexity.\t\t\t\t\t<\/div>\n\t\t\t\t<\/details>\n\t\t\t\t\t\t\t\t<details class=\"tlfaq__item\"  id=\"tlfaq-ee5e4958-ef01-40d6-8f4f-b38af9c6a1e3-1\">\n\t\t\t\t\t<summary class=\"tlfaq__question\">\n\t\t\t\t\t\t<span class=\"tlfaq__qtext\">Should testers start with brute force or optimized solutions?<\/span>\n\t\t\t\t\t\t<span class=\"tlfaq__icon\" aria-hidden=\"true\"><\/span>\n\t\t\t\t\t<\/summary>\n\t\t\t\t\t<div class=\"tlfaq__answer\">\n\t\t\t\t\t\tTesters should usually start with a brute-force solution unless the problem clearly demands optimization. This shows clear thinking and provides a baseline for improvement.\t\t\t\t\t<\/div>\n\t\t\t\t<\/details>\n\t\t\t\t\t\t\t\t<details class=\"tlfaq__item\"  id=\"tlfaq-ee5e4958-ef01-40d6-8f4f-b38af9c6a1e3-2\">\n\t\t\t\t\t<summary class=\"tlfaq__question\">\n\t\t\t\t\t\t<span class=\"tlfaq__qtext\">How many test cases should I mention in an interview?<\/span>\n\t\t\t\t\t\t<span class=\"tlfaq__icon\" aria-hidden=\"true\"><\/span>\n\t\t\t\t\t<\/summary>\n\t\t\t\t\t<div class=\"tlfaq__answer\">\n\t\t\t\t\t\tYou should mention at least three categories of test cases: positive, edge, and negative. If time allows, you can expand with additional scenarios.\t\t\t\t\t<\/div>\n\t\t\t\t<\/details>\n\t\t\t\t\t\t\t\t<details class=\"tlfaq__item\"  id=\"tlfaq-ee5e4958-ef01-40d6-8f4f-b38af9c6a1e3-3\">\n\t\t\t\t\t<summary class=\"tlfaq__question\">\n\t\t\t\t\t\t<span class=\"tlfaq__qtext\">What do interviewers look for besides the final answer?<\/span>\n\t\t\t\t\t\t<span class=\"tlfaq__icon\" aria-hidden=\"true\"><\/span>\n\t\t\t\t\t<\/summary>\n\t\t\t\t\t<div class=\"tlfaq__answer\">\n\t\t\t\t\t\tInterviewers also look for your reasoning, communication skills, debugging approach, and how well you validate your solution using test data.\t\t\t\t\t<\/div>\n\t\t\t\t<\/details>\n\t\t\t\t\t\t\t\t<details class=\"tlfaq__item\"  id=\"tlfaq-ee5e4958-ef01-40d6-8f4f-b38af9c6a1e3-4\">\n\t\t\t\t\t<summary class=\"tlfaq__question\">\n\t\t\t\t\t\t<span class=\"tlfaq__qtext\">How do I talk about time and space complexity in interviews?<\/span>\n\t\t\t\t\t\t<span class=\"tlfaq__icon\" aria-hidden=\"true\"><\/span>\n\t\t\t\t\t<\/summary>\n\t\t\t\t\t<div class=\"tlfaq__answer\">\n\t\t\t\t\t\tAfter explaining each approach, clearly state its time and space complexity and compare the trade-offs, such as speed versus memory usage.\t\t\t\t\t<\/div>\n\t\t\t\t<\/details>\n\t\t\t\t\t\t\t\t<details class=\"tlfaq__item\"  id=\"tlfaq-ee5e4958-ef01-40d6-8f4f-b38af9c6a1e3-5\">\n\t\t\t\t\t<summary class=\"tlfaq__question\">\n\t\t\t\t\t\t<span class=\"tlfaq__qtext\">What if I get stuck during a coding round?<\/span>\n\t\t\t\t\t\t<span class=\"tlfaq__icon\" aria-hidden=\"true\"><\/span>\n\t\t\t\t\t<\/summary>\n\t\t\t\t\t<div class=\"tlfaq__answer\">\n\t\t\t\t\t\tIf you get stuck, communicate your thought process, explain what you have already tried, and ask for hints. Many interviewers appreciate transparency and may guide you forward.\t\t\t\t\t<\/div>\n\t\t\t\t<\/details>\n\t\t\t\t\t\t<\/div>\n\n\t\t\t\t\t<script type=\"application\/ld+json\">\n\t\t\t\t{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"How do I approach coding questions in a QA interview?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Use a test-first mindset by first clarifying the requirements, identifying test data, proposing a brute-force solution, and then improving it while explaining the logic and complexity.\"}},{\"@type\":\"Question\",\"name\":\"Should testers start with brute force or optimized solutions?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Testers should usually start with a brute-force solution unless the problem clearly demands optimization. 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Many interviewers appreciate transparency and may guide you forward.\"}}]}\t\t\t<\/script>\n\t\t\t<\/div>\n\t\n<h5><strong>We Also Provide Training In:<\/strong><\/h5>\n<ul>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/selenium-automation-certification-training-course.html?utm_source=blog_post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>Advanced Selenium Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/playwright.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>Playwright Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/genai-qa-engineers-training-course.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>Gen AI Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/aws-cloud-architect-certification-training-course.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>AWS Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/rest-api-testing-certification-training-course.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>REST API Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/full-stack-developer-certification-training-course.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>Full Stack Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/appium-mobile-automation-certification-training-course.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>Appium Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/dev-ops-master-certification-training-course.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>DevOps Training<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.testleaf.com\/course\/apache-jmeter-testing-training-course.html?utm_source=blog-post&amp;utm_medium=Organic&amp;utm_campaign=Blog_Post\"><strong>JMeter Performance Training<\/strong><\/a><\/li>\n<\/ul>\n<div>\n<h6><strong>Author&#8217;s Bio<\/strong>:<\/h6>\n<p><img fetchpriority=\"high\" decoding=\"async\" class=\"size-full wp-image-2404 alignleft\" src=\"https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2023\/04\/Untitled-design.png\" alt=\"\" width=\"250\" height=\"250\" srcset=\"https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2023\/04\/Untitled-design.png 250w, https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2023\/04\/Untitled-design-150x150.png 150w, https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2023\/04\/Untitled-design-96x96.png 96w\" sizes=\"(max-width: 250px) 100vw, 250px\" \/><\/p>\n<p>As CEO of TestLeaf, I\u2019m dedicated to transforming software testing by empowering individuals with real-world skills and advanced technology. With 24+ years in software engineering, I lead our mission to shape local talent into global software professionals. Join us in redefining the future of test engineering and making a lasting impact in the tech world.<\/p>\n<p><strong>Babu Manickam<\/strong><\/p>\n<p><a href=\"https:\/\/in.linkedin.com\/in\/babu-manickam\" target=\"_blank\" rel=\"noopener\"><img decoding=\"async\" src=\"https:\/\/www.testleaf.com\/blog\/wp-content\/uploads\/2025\/07\/linkedin.png\" alt=\"LinkedIn Logo\" width=\"28\" height=\"28\" \/><\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp; This article is based on my recent 100+ real live interview experiences with my SDET learners with many product organizations in India. Skill up before you apply Suppose you are looking to become a high paid SDET. In that case, I recommend you to start solving 100\u2013150 easy\/medium DSA problems in Leetcode with a &hellip;<\/p>\n<p class=\"read-more\"> <a class=\"\" href=\"https:\/\/www.testleaf.com\/blog\/step-by-step-approach-to-solve-any-programming-questions-in-your-qa-interview\/\"> <span class=\"screen-reader-text\">Step by Step Approach to Solve Any Programming Questions in your QA Interview<\/span> Read More &raquo;<\/a><\/p>\n","protected":false},"author":1,"featured_media":187,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"site-sidebar-layout":"right-sidebar","site-content-layout":"plain-container","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","footnotes":""},"categories":[6],"tags":[102],"class_list":["post-186","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-general","tag-software-testing-course"],"acf":[],"aioseo_notices":[],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/posts\/186","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/comments?post=186"}],"version-history":[{"count":18,"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/posts\/186\/revisions"}],"predecessor-version":[{"id":9475,"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/posts\/186\/revisions\/9475"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/media\/187"}],"wp:attachment":[{"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/media?parent=186"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/categories?post=186"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.testleaf.com\/blog\/wp-json\/wp\/v2\/tags?post=186"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}