{"id":8912,"date":"2025-08-04T11:07:56","date_gmt":"2025-08-04T05:37:56","guid":{"rendered":"https:\/\/namastedev.com\/blog\/?p=8912"},"modified":"2025-08-04T11:09:21","modified_gmt":"2025-08-04T05:39:21","slug":"binary-tree-right-side-view","status":"publish","type":"post","link":"https:\/\/namastedev.com\/blog\/binary-tree-right-side-view\/","title":{"rendered":"Binary Tree Right Side View"},"content":{"rendered":"\n<!-- Binary Side view: 23 -->\n<link\n    href=\"https:\/\/cdn.jsdelivr.net\/npm\/prismjs@1.29.0\/themes\/prism-tomorrow.min.css\"\n    rel=\"stylesheet\"\n\/>\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/prismjs@1.29.0\/prism.min.js\"><\/script>\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/prismjs@1.29.0\/plugins\/autoloader\/prism-autoloader.min.js\"><\/script>\n\n<style> \n.wp_blog_theme {\n  --primary: #E58C32;\n  --secondary: #f8c291;\n  --light-bg: #fef9f4;\n  --text-dark: #2d2d2d;\n  --tab-radius: 12px;\n  --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);\n  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0;\n  padding: 1.5rem;\n  font-size: 1rem;\n  overflow-x: auto;\n  background: var(--code-bg);\n  border-radius: var(--tab-radius);\n  color: var(--code-text);\n}\n<\/style>\n\n<div class=\"wp_blog_container wp_blog_theme\"> \n    <h1 class=\"wp_blog_main-heading\"><\/h1>\n    <div class=\"wp_blog_explanation\">\n        <h2>Problem Statement:<\/h2>\n        <p>Given the <code>root<\/code> of a binary tree, imagine yourself standing on the <strong>right side<\/strong> of it, return the values of the nodes you can see ordered from top to bottom.<\/p>\n        \n        <h2>Examples:<\/h2>\n                <h3>Example 1:<\/h3>\n                <p><strong>Input:<\/strong>  root = [1,2,3,null,5,null,4]<\/p>\n                <p><strong>Output:<\/strong> [1,3,4]<\/p>\n                <p><strong>Explanation:<\/strong>\n                    <img decoding=\"async\" src=\"https:\/\/namastedev.com\/blog\/wp-content\/uploads\/2025\/08\/Screenshot-2025-08-04-at-9.57.55\u202fAM.png\" alt=\"\">\n                <\/p>\n\n               <h3>Example 2:<\/h3>\n                <p><strong>Input:<\/strong>  root = [1,2,3,4,null,null,null,5]<\/p>\n                <p><strong>Output:<\/strong> [1,3,4,5]<\/p>\n                <p><strong>Explanation:<\/strong>\n                    <img decoding=\"async\" src=\"https:\/\/namastedev.com\/blog\/wp-content\/uploads\/2025\/08\/Screenshot-2025-08-04-at-9.58.10\u202fAM.png\" alt=\"\">\n                <\/p> \n                \n                <h3>Example 3:<\/h3>\n                <p><strong>Input:<\/strong> root = [1,null,3]<\/p>\n                <p><strong>Output:<\/strong> [1,3]<\/p>\n\n                <h3>Example 4:<\/h3>\n                <p><strong>Input:<\/strong> root = []<\/p>\n                <p><strong>Output:<\/strong> []<\/p>\n\n\n                    <h2>Constraints:<\/h2>\n                    <ul>\n                        <li>The number of nodes in the tree is in the range <code>[0, 100]<\/code>.<\/li>\n                        <li><code>-100 <= Node.val <= 100<\/code><\/li>\n                    <\/ul>\n\n                <h2>Approach<\/h2>\n                <ul>\n                    <li>If the tree is empty, return an empty array.<\/li>\n                    <li>Use a queue <code>q<\/code> for <strong>level-order traversal (BFS)<\/strong>.<\/li>\n                    <li>For each level:\n                        <ul>\n                            <li>Store the number of nodes (<code>levelSize<\/code>).<\/li>\n                            <li>Traverse all nodes at this level.<\/li>\n                            <li>Since you <strong>push right first<\/strong>, the <strong>first node<\/strong> (<code>i == 0<\/code>) <strong>is the rightmost node<\/strong> of that level \u2192 store it in <code>ans<\/code>.<\/li>\n                            <li>Push <code>right<\/code> child first, then <code>left<\/code>, to ensure rightmost nodes are visited first in the next level.<\/li>\n                        <\/ul>\n                    <\/li>\n                <\/ul>\n\n                <h2>Time Complexity:<\/h2>\n                <li>\n                  <p><strong>Time Complexity = O(n)<\/strong>\n                  <\/li>\n                <h2>Space Complexity:<\/h2>\n                <li>\n                  <p><strong>Space Complexity = O(w)<\/strong> Where w is the <strong>maximum width<\/strong> of the tree<\/p>\n                <\/li>\n<h2>Dry Run<\/h2> <div style=\"background: #f9f9f9; padding: 10px; border: 1px solid #ccc; font-family: monospace;\"> <b>Function Call:<\/b> rightSideView(root) where<br> root = TreeNode(1)<br> \u251c\u2500\u2500 left: TreeNode(2)<br> \u2502\u00a0\u00a0 \u2514\u2500\u2500 right: TreeNode(5)<br> \u2514\u2500\u2500 right: TreeNode(3)<br> \u00a0\u00a0 \u2514\u2500\u2500 right: TreeNode(4)<br><br>\n<b>Step 1:<\/b><br>\n\u2192 Initialize ans = []<br>\n\u2192 Initialize q = [1]<br><br>\n<b>Step 2 (First Level):<\/b><br>\n\u2192 levelSize = 1<br>\n\u2192 i = 0<br>\n\u2192 curr = 1<br>\n\u2192 i == 0 \u2192 ans.push(1) \u2192 ans = [1]<br>\n\u2192 curr.right = 3 \u2192 q.push(3)<br>\n\u2192 curr.left = 2 \u2192 q.push(2)<br><br>\n\n<b>Step 3 (Second Level):<\/b><br>\n\u2192 q = [3, 2]<br>\n\u2192 levelSize = 2<br>\n\u2192 i = 0<br>\n\u2192 curr = 3<br>\n\u2192 i == 0 \u2192 ans.push(3) \u2192 ans = [1, 3]<br>\n\u2192 curr.right = 4 \u2192 q.push(4)<br>\n\u2192 curr.left = null<br>\n\u2192 i = 1<br>\n\u2192 curr = 2<br>\n\u2192 curr.right = 5 \u2192 q.push(5)<br>\n\u2192 curr.left = null<br><br>\n\n<b>Step 4 (Third Level):<\/b><br>\n\u2192 q = [4, 5]<br>\n\u2192 levelSize = 2<br>\n\u2192 i = 0<br>\n\u2192 curr = 4<br>\n\u2192 i == 0 \u2192 ans.push(4) \u2192 ans = [1, 3, 4]<br>\n\u2192 curr.right = null<br>\n\u2192 curr.left = null<br>\n\u2192 i = 1<br>\n\u2192 curr = 5<br>\n\u2192 curr.right = null<br>\n\u2192 curr.left = null<br><br>\n\n<b>Step 5:<\/b><br>\n\u2192 q = [] \u2192 loop ends<br><br>\n\n<b>Final Result:<\/b> [1, 3, 4]\n\n<\/div>\n    <!-- <h2>Visualisation:<\/h2>\n        <img decoding=\"async\" src=\"https:\/\/namastedev.com\/blog\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-19-at-5.23.43\u202fPM.png\" alt=\"longest\" \/> -->\n    <\/div>\n    \n\n    <div class=\"wp_blog_code-tabs-container\">\n        <div class=\"wp_blog_code-tabs-header\">\n            <button class=\"wp_blog_code-tab-button active\" data-lang=\"js\">JavaScript<\/button>\n            <button class=\"wp_blog_code-tab-button\" data-lang=\"py\">Python<\/button>\n            <button class=\"wp_blog_code-tab-button\" data-lang=\"java\">Java<\/button>\n            <button class=\"wp_blog_code-tab-button\" data-lang=\"cpp\">C++<\/button>\n            <button class=\"wp_blog_code-tab-button\" data-lang=\"c\">C<\/button>\n            <button class=\"wp_blog_code-tab-button\" data-lang=\"cs\">C#<\/button>\n        <\/div>\n\n        <!-- JavaScript -->\n        <div class=\"wp_blog_code-tab-content active\" data-lang=\"js\">\n            <pre><code class=\"language-javascript\">\nvar rightSideView = function(root) {\n    if (!root) return [];\n    let ans = [];\n    let q = [root];\n    while (q.length) {\n        let levelSize = q.length;\n        for (let i = 0; i < levelSize; i++) {\n            let curr = q.shift();\n            if (i === 0) {\n                ans.push(curr.val);\n            }\n            if (curr.right) q.push(curr.right);\n            if (curr.left) q.push(curr.left);\n        }\n    }\n    return ans;\n};   <\/code><\/pre>\n        <\/div>\n\n        <!-- Python -->\n        <div class=\"wp_blog_code-tab-content\" data-lang=\"py\">\n            <pre><code class=\"language-python\">\ndef rightSideView(root):\n    if not root:\n        return []\n    ans = []\n    q = [root]\n    while q:\n        level_size = len(q)\n        for i in range(level_size):\n            curr = q.pop(0)\n            if i == 0:\n                ans.append(curr.val)\n            if curr.right:\n                q.append(curr.right)\n            if curr.left:\n                q.append(curr.left)\n    return ans\n            <\/code><\/pre>\n        <\/div>\n\n        <!-- Java -->\n        <div class=\"wp_blog_code-tab-content\" data-lang=\"java\">\n            <pre><code class=\"language-java\">\npublic List<Integer> rightSideView(TreeNode root) {\n    List<Integer> ans = new ArrayList<>();\n    if (root == null) return ans;\n    Queue<TreeNode> q = new LinkedList<>();\n    q.add(root);\n\n    while (!q.isEmpty()) {\n        int levelSize = q.size();\n        for (int i = 0; i < levelSize; i++) {\n            TreeNode curr = q.poll();\n            if (i == 0) ans.add(curr.val);\n            if (curr.right != null) q.add(curr.right);\n            if (curr.left != null) q.add(curr.left);\n        }\n    }\n    return ans;\n}\n     <\/code><\/pre>\n        <\/div>\n\n        <!-- C++ -->\n        <div class=\"wp_blog_code-tab-content\" data-lang=\"cpp\">\n            <pre><code class=\"language-cpp\">\nvector<int> rightSideView(TreeNode* root) {\n    vector<int> ans;\n    if (!root) return ans;\n    queue<TreeNode*> q;\n    q.push(root);\n    \n    while (!q.empty()) {\n        int levelSize = q.size();\n        for (int i = 0; i < levelSize; ++i) {\n            TreeNode* curr = q.front();\n            q.pop();\n            if (i == 0) ans.push_back(curr->val);\n            if (curr->right) q.push(curr->right);\n            if (curr->left) q.push(curr->left);\n        }\n    }\n    return ans;\n}\n    <\/code><\/pre>\n        <\/div>\n\n        <!-- C -->\n        <div class=\"wp_blog_code-tab-content\" data-lang=\"c\">\n            <pre><code class=\"language-c\">\ntypedef struct TreeNode {\n    int val;\n    struct TreeNode *left;\n    struct TreeNode *right;\n} TreeNode;\ntypedef struct Queue {\n    TreeNode** data;\n    int front, rear, size, capacity;\n} Queue;\n\n\/\/ Implement queue functions here...\nvoid rightSideView(TreeNode* root, int* result, int* returnSize) {\n    if (!root) {\n        *returnSize = 0;\n        return;\n    }\n    Queue* q = createQueue(100);\n    enqueue(q, root);\n    int idx = 0;\n    while (!isEmpty(q)) {\n        int levelSize = q->size;\n        for (int i = 0; i < levelSize; i++) {\n            TreeNode* curr = dequeue(q);\n            if (i == 0)\n                result[idx++] = curr->val;\n            if (curr->right) enqueue(q, curr->right);\n            if (curr->left) enqueue(q, curr->left);\n        }\n    }\n    *returnSize = idx;\n}\n            <\/code><\/pre>\n        <\/div>\n\n        <!-- C# -->\n        <div class=\"wp_blog_code-tab-content\" data-lang=\"cs\">\n            <pre><code class=\"language-csharp\">\npublic IList<int> RightSideView(TreeNode root) {\n    List<int> ans = new List<int>();\n    if (root == null) return ans;\n    Queue<TreeNode> q = new Queue<TreeNode>();\n    q.Enqueue(root);\n    while (q.Count > 0) {\n        int levelSize = q.Count;\n        for (int i = 0; i < levelSize; i++) {\n            TreeNode curr = q.Dequeue();\n            if (i == 0) ans.Add(curr.val);\n            if (curr.right != null) q.Enqueue(curr.right);\n            if (curr.left != null) q.Enqueue(curr.left);\n        }\n    }\n    return ans;\n}\n            <\/code><\/pre>\n        <\/div>\n    <\/div>\n<\/div>\n\n<script>\n    document.addEventListener(\"DOMContentLoaded\", () => {\n        const buttons = document.querySelectorAll(\".wp_blog_code-tab-button\");\n        const contents = document.querySelectorAll(\".wp_blog_code-tab-content\");\n\n        buttons.forEach((button) => {\n            button.addEventListener(\"click\", () => {\n                const lang = button.getAttribute(\"data-lang\");\n\n                buttons.forEach((btn) => btn.classList.remove(\"active\"));\n                contents.forEach((content) =>\n                    content.classList.remove(\"active\")\n                );\n\n                button.classList.add(\"active\");\n         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Examples: Example 1: Input: root = [1,2,3,null,5,null,4] Output: [1,3,4] Explanation: Example 2: Input: root = [1,2,3,4,null,null,null,5] Output: [1,3,4,5] Explanation: Example 3: Input: root<\/p>\n","protected":false},"author":108,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[210,322,176,175,211,811,810,174,172,173],"tags":[],"class_list":["post-8912","post","type-post","status-publish","format-standard","category-algorithms","category-algorithms-and-data-structures","category-csharp","category-cplusplus","category-data-structures","category-data-structures-and-algorithms","category-dsa","category-java","category-javascript","category-python"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/8912","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/users\/108"}],"replies":[{"embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/comments?post=8912"}],"version-history":[{"count":1,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/8912\/revisions"}],"predecessor-version":[{"id":8913,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/8912\/revisions\/8913"}],"wp:attachment":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/media?parent=8912"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/categories?post=8912"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/tags?post=8912"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}