{"id":6875,"date":"2022-07-28T23:15:00","date_gmt":"2022-07-28T17:45:00","guid":{"rendered":"https:\/\/www.codingbroz.com\/?p=6875"},"modified":"2022-07-02T19:56:11","modified_gmt":"2022-07-02T14:26:11","slug":"merge-two-sorted-lists-leetcode-solution","status":"publish","type":"post","link":"https:\/\/www.codingbroz.com\/merge-two-sorted-lists-leetcode-solution\/","title":{"rendered":"Merge Two Sorted Lists &#8211; Leetcode Solution"},"content":{"rendered":"\n<p>In this post, we are going to solve the<strong> 21. Merge Two Sorted Lists<\/strong> problem of Leetcode. This problem <strong><strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong><\/strong> is a Leetcode <strong>easy <\/strong>level problem. Let&#8217;s see the code, <strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong> <strong>&#8211; Leetcode Solution<\/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-6635d60ad5d2a\" 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-6635d60ad5d2a\" 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\/merge-two-sorted-lists-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\/merge-two-sorted-lists-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\/merge-two-sorted-lists-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\/merge-two-sorted-lists-leetcode-solution\/#Example_3\" title=\"Example 3 :\">Example 3 :<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.codingbroz.com\/merge-two-sorted-lists-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-6\" href=\"https:\/\/www.codingbroz.com\/merge-two-sorted-lists-leetcode-solution\/#Merge_Two_Sorted_Lists_%E2%80%93_Leetcode_Solution\" title=\"Merge Two Sorted Lists &#8211; Leetcode Solution\">Merge Two Sorted Lists &#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-7\" href=\"https:\/\/www.codingbroz.com\/merge-two-sorted-lists-leetcode-solution\/#21_Merge_Two_Sorted_Lists_%E2%80%93_Solution_in_Java\" title=\"21. Merge Two Sorted Lists &#8211; Solution in Java\">21. Merge Two Sorted Lists &#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-8\" href=\"https:\/\/www.codingbroz.com\/merge-two-sorted-lists-leetcode-solution\/#21_Merge_Two_Sorted_Lists_%E2%80%93_Solution_in_C\" title=\"21. Merge Two Sorted Lists &#8211; Solution in C++\">21. Merge Two Sorted Lists &#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-9\" href=\"https:\/\/www.codingbroz.com\/merge-two-sorted-lists-leetcode-solution\/#21_Merge_Two_Sorted_Lists_%E2%80%93_Solution_in_Python\" title=\"21. Merge Two Sorted Lists &#8211; Solution in Python\">21. Merge Two Sorted Lists &#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>You are given the heads of two sorted linked lists <code>list1<\/code> and <code>list2<\/code>.<\/p>\n\n\n\n<p>Merge the two lists in a one <strong>sorted<\/strong> list. The list should be made by splicing together the nodes of the first two lists.<\/p>\n\n\n\n<p>Return <em>the head of the merged linked list<\/em>.<\/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>Input: list1 = &#91;1,2,4], list2 = &#91;1,3,4]\r\nOutput: &#91;1,1,2,3,4,4]<\/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>Input: list1 = &#91;], list2 = &#91;]\r\nOutput: &#91;]<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Example_3\"><\/span>E<strong>xample 3 :<\/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>Input: list1 = &#91;], list2 = &#91;0]\r\nOutput: &#91;0]<\/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>The number of nodes in both lists is in the range <code>[0, 50]<\/code>.<\/li><li><code>-100 &lt;= Node.val &lt;= 100<\/code><\/li><li>Both <code>list1<\/code> and <code>list2<\/code> are sorted in <strong>non-decreasing<\/strong> order.<\/li><\/ul>\n\n\n\n<p>Now, let&#8217;s see the code of <strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong> &#8211; Leetcode Solution.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Merge_Two_Sorted_Lists_%E2%80%93_Leetcode_Solution\"><\/span><strong><strong>Merge Two Sorted Lists &#8211; Leetcode Solution<\/strong><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"21_Merge_Two_Sorted_Lists_%E2%80%93_Solution_in_Java\"><\/span><strong><strong><strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong><\/strong> &#8211; Solution in Java<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>This is the <strong>Iterative Approach<\/strong> to the solution of <strong><strong><strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong><\/strong><\/strong> in Java Programming Language.<\/p>\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=\"\">\/**\n * Definition for singly-linked list.\n * public class ListNode {\n *     int val;\n *     ListNode next;\n *     ListNode() {}\n *     ListNode(int val) { this.val = val; }\n *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }\n * }\n *\/\npublic class Solution {\n    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {\n        ListNode head = new ListNode(0);\n        ListNode handler = head;\n        while(l1 != null &amp;&amp; l2 != null) {\n            if (l1.val &lt;= l2.val) {\n                handler.next = l1;\n                l1 = l1.next;\n            } else {\n                handler.next = l2;\n                l2 = l2.next;\n            }\n            handler = handler.next;\n        }\n        \n        if (l1 != null) {\n            handler.next = l1;\n        } else if (l2 != null) {\n            handler.next = l2;\n        }\n        \n        return head.next;\n    }\n}<\/pre>\n\n\n\n<p>Now let&#8217;s see the <strong>Recursive approach<\/strong> to solve the same problem in <strong>Java<\/strong> using <strong>Recursion<\/strong>.<\/p>\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=\"\">\/**\n * Definition for singly-linked list.\n * public class ListNode {\n *     int val;\n *     ListNode next;\n *     ListNode() {}\n *     ListNode(int val) { this.val = val; }\n *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }\n * }\n *\/\npublic class Solution {\n    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {\n        if (l1 == null) return l2;\n        if (l2 == null) return l1;\n        \n        ListNode handler;\n        if(l1.val &lt; l2.val) {\n            handler = l1;\n            handler.next = mergeTwoLists(l1.next, l2);\n        } else {\n            handler = l2;\n            handler.next = mergeTwoLists(l1, l2.next);\n        }\n        \n        return handler;\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"21_Merge_Two_Sorted_Lists_%E2%80%93_Solution_in_C\"><\/span><strong><strong><strong><strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong><\/strong> &#8211; Solution in <\/strong>C++<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>This is the <strong>Iterative Approach<\/strong> to the solution of <strong><strong><strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong><\/strong><\/strong> in C++ Programming Language.<\/p>\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=\"\">\/**\n * Definition for singly-linked list.\n * struct ListNode {\n *     int val;\n *     ListNode *next;\n *     ListNode() : val(0), next(nullptr) {}\n *     ListNode(int x) : val(x), next(nullptr) {}\n *     ListNode(int x, ListNode *next) : val(x), next(next) {}\n * };\n *\/\nclass Solution {\npublic:\n    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {\n       ListNode* temp = new ListNode(-1);\n        ListNode* head = temp;\n        while(l1!=NULL and l2!=NULL){\n            if(l1->val&lt;=l2->val){\n                head->next = l1;\n                l1 = l1->next;\n            }\n            else {\n                head->next = l2;\n                l2 = l2->next;\n            }\n            head=head->next;\n        }\n        if(l1!=NULL)\n        {\n            head->next = l1;\n        }\n        else head->next = l2;\n        \n        return temp->next;\n    }\n};<\/pre>\n\n\n\n<p>Now let&#8217;s see the <strong>Recursive approach<\/strong> to solve the same problem in <strong>C++<\/strong> using <strong>Recursion<\/strong>.<\/p>\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=\"\">\/**\n * Definition for singly-linked list.\n * struct ListNode {\n *     int val;\n *     ListNode *next;\n *     ListNode() : val(0), next(nullptr) {}\n *     ListNode(int x) : val(x), next(nullptr) {}\n *     ListNode(int x, ListNode *next) : val(x), next(next) {}\n * };\n *\/\nclass Solution {\npublic:\n\tListNode* mergeTwoLists(ListNode* l1, ListNode* l2) \n        {\n\t\t\n\t\tif(l1 == NULL)\n                {\n\t\t\treturn l2;\n\t\t}\n\t\t\n\t\tif(l2 == NULL)\n                {\n\t\t\treturn l1;\n\t\t} \n\t\t\n\t\t\n\t\tif(l1 -> val &lt;= l2 -> val)\n                {\n\t\t\tl1 -> next = mergeTwoLists(l1 -> next, l2);\n\t\t\treturn l1;\n\t\t}\n\t\t\n\t\telse\n                {\n\t\t\tl2 -> next = mergeTwoLists(l1, l2 -> next);\n\t\t\treturn l2;            \n\t\t}\n\t}\n};\t<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"21_Merge_Two_Sorted_Lists_%E2%80%93_Solution_in_Python\"><\/span><strong><strong><strong><strong><strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong><\/strong> &#8211; Solution in <\/strong><\/strong>Python<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>This is the <strong>Iterative Approach<\/strong> to the solution of <strong><strong><strong><strong>21. Merge Two Sorted Lists<\/strong><\/strong><\/strong><\/strong> in Python Programming Language.<\/p>\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=\"\"># Definition for singly-linked list.\n# class ListNode(object):\n#     def __init__(self, val=0, next=None):\n#         self.val = val\n#         self.next = next\ndef mergeTwoLists1(self, l1, l2):\n    dummy = cur = ListNode(0)\n    while l1 and l2:\n        if l1.val &lt; l2.val:\n            cur.next = l1\n            l1 = l1.next\n        else:\n            cur.next = l2\n            l2 = l2.next\n        cur = cur.next\n    cur.next = l1 or l2\n    return dummy.next<\/pre>\n\n\n\n<p>Now let&#8217;s see the <strong>Recursive approach<\/strong> to solve the same problem in Python using <strong>Recursion<\/strong>.<\/p>\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=\"\"># Definition for singly-linked list.\n# class ListNode(object):\n#     def __init__(self, val=0, next=None):\n#         self.val = val\n#         self.next = next\ndef mergeTwoLists2(self, l1, l2):\n    if not l1 or not l2:\n        return l1 or l2\n    if l1.val &lt; l2.val:\n        l1.next = self.mergeTwoLists(l1.next, l2)\n        return l1\n    else:\n        l2.next = self.mergeTwoLists(l1, l2.next)\n        return l2<\/pre>\n\n\n\n<p><strong>Note:<\/strong> This problem <strong><strong><a href=\"https:\/\/leetcode.com\/problems\/merge-two-sorted-lists\/\" target=\"_blank\" rel=\"noreferrer noopener\">21. Merge Two Sorted Lists<\/a><\/strong><\/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 21. Merge Two Sorted Lists problem of Leetcode. This problem 21. Merge Two Sorted Lists is a Leetcode easy level problem. Let&#8217;s see the code, 21. Merge Two Sorted Lists &#8211; Leetcode Solution.<\/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":[130,689,710],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/posts\/6875"}],"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=6875"}],"version-history":[{"count":3,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/posts\/6875\/revisions"}],"predecessor-version":[{"id":6881,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/posts\/6875\/revisions\/6881"}],"wp:attachment":[{"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/media?parent=6875"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/categories?post=6875"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.codingbroz.com\/wp-json\/wp\/v2\/tags?post=6875"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}