{"id":8267,"date":"2022-10-20T23:20:00","date_gmt":"2022-10-20T17:50:00","guid":{"rendered":"https:\/\/www.codingbroz.com\/?p=8267"},"modified":"2022-10-20T09:55:19","modified_gmt":"2022-10-20T04:25:19","slug":"4sum-leetcode-solution","status":"publish","type":"post","link":"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/","title":{"rendered":"4Sum &#8211; Leetcode Solution"},"content":{"rendered":"\n<p>In this post, we are going to solve the<strong> 18. 4Sum<\/strong> problem of Leetcode. This problem <strong>18. 4Sum<\/strong> is a Leetcode <strong>medium <\/strong>level problem. Let&#8217;s see code, <strong>18. 4Sum<\/strong>.<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_65 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<label for=\"ez-toc-cssicon-toggle-item-6636508d1c5e5\" class=\"ez-toc-cssicon-toggle-label\"><label class=\"ez-toc-title\">Table of Contents<\/label>\n<span class=\"ez-toc-cssicon\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #0090ff;color:#0090ff\" 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: #0090ff;color:#0090ff\" 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><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-6636508d1c5e5\" checked \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#Problem\" title=\"Problem\">Problem<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#Example_1\" title=\"Example 1 :\">Example 1 :<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#Example_2\" title=\"Example 2 :\">Example 2 :<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#Constraints\" title=\"Constraints\">Constraints<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#4Sum_%E2%80%93_Leetcode_Solution\" title=\"4Sum &#8211; Leetcode Solution\">4Sum &#8211; Leetcode Solution<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#18_4Sum_%E2%80%93_Solution_in_Java\" title=\"18. 4Sum &#8211; Solution in Java\">18. 4Sum &#8211; Solution in Java<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#18_4Sum_%E2%80%93_Solution_in_C\" title=\"18. 4Sum &#8211; Solution in C++\">18. 4Sum &#8211; Solution in C++<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.codingbroz.com\/4sum-leetcode-solution\/#18_4Sum_%E2%80%93_Solution_in_Python\" title=\"18. 4Sum &#8211; Solution in Python\">18. 4Sum &#8211; Solution in Python<\/a><\/li><\/ul><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Problem\"><\/span><strong>Problem<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Given an array <code>nums<\/code> of <code>n<\/code> integers, return <em>an array of all the <strong>unique<\/strong> quadruplets<\/em> <code>[nums[a], nums[b], nums[c], nums[d]]<\/code> such that:<\/p>\n\n\n\n<ul><li><code>0 &lt;= a, b, c, d &lt; n<\/code><\/li><li><code>a<\/code>, <code>b<\/code>, <code>c<\/code>, and <code>d<\/code> are <strong>distinct<\/strong>.<\/li><li><code>nums[a] + nums[b] + nums[c] + nums[d] == target<\/code><\/li><\/ul>\n\n\n\n<p>You may return the answer in <strong>any order<\/strong>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Example_1\"><\/span><strong>Example 1 :<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"wp-block-code has-ast-global-color-5-color has-ast-global-color-8-background-color has-text-color has-background\"><code>\nInput: nums = &#91;1,0,-1,0,-2,2], target = 0\r\nOutput: &#91;&#91;-2,-1,1,2],&#91;-2,0,0,2],&#91;-1,0,0,1]]\n<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Example_2\"><\/span><strong>Example 2 :<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"wp-block-code has-ast-global-color-5-color has-ast-global-color-8-background-color has-text-color has-background\"><code>\nInput: nums = &#91;2,2,2,2,2], target = 8\r\nOutput: &#91;&#91;2,2,2,2]]\n<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Constraints\"><\/span><strong>Constraints<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul><li><code>1 &lt;= nums.length &lt;= 200<\/code><\/li><li><code><code>-10<sup>9<\/sup> &lt;= <code>nums<\/code><\/code><\/code>[i]<code><code> &lt;= 10<sup>9<\/sup><\/code><\/code><\/li><li><code>-10<sup>9<\/sup> &lt;= target &lt;= 10<sup>9<\/sup><\/code><\/li><\/ul>\n\n\n\n<p>Now, let&#8217;s see the code of <strong>18. 4Sum<\/strong> &#8211; Leetcode Solution.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"4Sum_%E2%80%93_Leetcode_Solution\"><\/span><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong>4Sum<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong> &#8211; Leetcode Solution<span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"18_4Sum_%E2%80%93_Solution_in_Java\"><\/span><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong>18. 4Sum<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong> &#8211; Solution in Java<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"java\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Solution {\n    public List&lt;List&lt;Integer>> fourSum(int[] nums, int target) {\n      int n = nums.length;\n      Arrays.sort(nums);\n      List&lt;List&lt;Integer>> result = new ArrayList&lt;>();\n      for (int i = 0; i &lt; n; ++i) {\n        if (i > 0 &amp;&amp; nums[i - 1] == nums[i]) continue;\n        threeSum(nums, i + 1, n - 1, target - nums[i], result);\n      }\n      return result;\n    }\n  \n    private void threeSum(int[] nums, int lo, int hi, int target, List&lt;List&lt;Integer>> result) {\n      int n = nums.length;\n      int subLen = hi - lo + 1;\n      for (int i = lo; i &lt;= hi; ++i) {\n        if (i > lo &amp;&amp; nums[i] == nums[i - 1]) continue;  \n        int j = i + 1, k = hi;\n        int t = target - nums[i];\n        while (j &lt; k) { \n          if (nums[j] + nums[k] &lt; t) {\n            ++j;\n          } else if (nums[j] + nums[k] > t) {\n            --k;\n          } else { \n            result.add(Arrays.asList(nums[lo - 1], nums[i], nums[j], nums[k]));\n            ++j;\n            --k;\n            while (j &lt; k &amp;&amp; nums[j] == nums[j - 1]) j++;  \n            while (j &lt; k &amp;&amp; nums[k] == nums[k + 1]) k--;  \n          }\n        }\n    }\n}\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"18_4Sum_%E2%80%93_Solution_in_C\"><\/span><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong>18. 4Sum<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong> &#8211; Solution in <\/strong>C++<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"cpp\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Solution {\npublic:\n    vector&lt;vector&lt;int>> fourSum(vector&lt;int>&amp; nums, int target) {\n        vector&lt;vector&lt;int>> total;\n        int n = nums.size();\n        if(n&lt;4)  return total;\n        sort(nums.begin(),nums.end());\n        for(int i=0;i&lt;n-3;i++)\n        {\n            if(i>0&amp;&amp;nums[i]==nums[i-1]) continue;\n            if(nums[i]+nums[i+1]+nums[i+2]+nums[i+3]>target) break;\n            if(nums[i]+nums[n-3]+nums[n-2]+nums[n-1]&lt;target) continue;\n            for(int j=i+1;j&lt;n-2;j++)\n            {\n                if(j>i+1&amp;&amp;nums[j]==nums[j-1]) continue;\n                if(nums[i]+nums[j]+nums[j+1]+nums[j+2]>target) break;\n                if(nums[i]+nums[j]+nums[n-2]+nums[n-1]&lt;target) continue;\n                int left=j+1,right=n-1;\n                while(left&lt;right){\n                    int sum=nums[left]+nums[right]+nums[i]+nums[j];\n                    if(sum&lt;target) left++;\n                    else if(sum>target) right--;\n                    else{\n                        total.push_back(vector&lt;int>{nums[i],nums[j],nums[left],nums[right]});\n                        do{left++;}while(nums[left]==nums[left-1]&amp;&amp;left&lt;right);\n                        do{right--;}while(nums[right]==nums[right+1]&amp;&amp;left&lt;right);\n                    }\n                }\n            }\n        }\n        return total;\n    }\n};<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"18_4Sum_%E2%80%93_Solution_in_Python\"><\/span><strong>18. 4Sum<\/strong> <strong><strong><strong>&#8211; Solution in <\/strong><\/strong>Python<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"python\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Solution:\n    def fourSum(self, num, target):\n        two_sum = collections.defaultdict(list)\n        res = set()\n        for (n1, i1), (n2, i2) in itertools.combinations(enumerate(num), 2):\n            two_sum[i1+i2].append({n1, n2})\n        for t in list(two_sum.keys()):\n            if not two_sum[target-t]:\n                continue\n            for pair1 in two_sum[t]:\n                for pair2 in two_sum[target-t]:\n                    if pair1.isdisjoint(pair2):\n                        res.add(tuple(sorted(num[i] for i in pair1 | pair2)))\n            del two_sum[t]\n        return [list(r) for r in res]<\/pre>\n\n\n\n<p><strong>Note:<\/strong> This problem <strong><a href=\"https:\/\/leetcode.com\/problems\/4sum\/\" target=\"_blank\" rel=\"noreferrer noopener\">18. 4Sum<\/a><\/strong> is generated by <strong><a href=\"https:\/\/leetcode.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">Leetcode<\/a> <\/strong>but the solution is provided by <strong><a href=\"https:\/\/www.codingbroz.com\/\">CodingBroz<\/a><\/strong>. This tutorial is only for <strong>Educational<\/strong> and <strong>Learning<\/strong> purpose.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In this post, we are going to solve the 18. 4Sum problem of Leetcode. This problem 18. 4Sum is a Leetcode medium level problem. Let&#8217;s see code, 18. 4Sum.<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","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":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[688],"tags":[804,130,689],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/posts\/8267"}],"collection":[{"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/comments?post=8267"}],"version-history":[{"count":2,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/posts\/8267\/revisions"}],"predecessor-version":[{"id":8269,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/posts\/8267\/revisions\/8269"}],"wp:attachment":[{"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/media?parent=8267"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/categories?post=8267"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/tags?post=8267"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}