{"id":7280,"date":"2025-06-25T23:33:03","date_gmt":"2025-06-25T18:03:03","guid":{"rendered":"https:\/\/namastedev.com\/blog\/?p=7280"},"modified":"2025-09-29T19:00:53","modified_gmt":"2025-09-29T13:30:53","slug":"reversestring","status":"publish","type":"post","link":"https:\/\/namastedev.com\/blog\/reversestring\/","title":{"rendered":"Reverse String"},"content":{"rendered":"\n\n\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: #030302;\n  --light-bg: #fef9f4;\n  --text-dark: #2d2d2d;\n  --tab-radius: 12px;\n  --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);\n  --code-bg: #001f3f;\n  --code-text: #d4f1ff;\n}\n\n.wp_blog_container {\n  font-family: 'Segoe UI', sans-serif;\n  background: var(--light-bg);\n  margin: 0;\n  padding: 0;\n  color: var(--text-dark);\n}\n\n\/* Heading *\/\n.wp_blog_main-heading {\n  text-align: center;\n  font-size: 2.4rem;\n  color: var(--primary);\n  margin-top: 2.5rem;\n  font-weight: bold;\n}\n\n\/* Explanation Card *\/\n.wp_blog_explanation,\n.wp_blog_code-tabs-container {\n  max-width: 940px;\n  margin: 2rem auto;\n  padding: 2rem;\n  background: white;\n  border-radius: var(--tab-radius);\n  box-shadow: var(--shadow);\n}\n\n\/* Text and Visuals *\/\n.wp_blog_explanation h2 {\n  font-size: 1.4rem;\n  color: var(--primary);\n  margin-bottom: 0.5rem;\n}\n\n.wp_blog_explanation p,\n.wp_blog_explanation li {\n  font-size: 1.05rem;\n  line-height: 1.7;\n  margin: 0.5rem 0;\n}\n\n.wp_blog_explanation code {\n  background: #fef9f4;   \/* light bg instead of dark blue *\/\n  color: #E58C32;        \/* brand orange *\/\n  padding: 3px 6px;\n  border-radius: 4px;\n  font-family: 'Courier New', monospace;\n  font-weight: 600;      \/* optional, makes it pop *\/\n}\n\n.wp_blog_explanation img {\n  max-width: 100%;\n  border-radius: var(--tab-radius);\n  margin-top: 1rem;\n  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);\n}\n\n\/* Tab Buttons *\/\n.wp_blog_code-tabs-header {\n  display: flex;\n  flex-wrap: wrap;\n  gap: 0.5rem;\n  margin-bottom: 1rem;\n}\n\n.wp_blog_code-tab-button {\n  padding: 0.6rem 1.2rem;\n  border: 1px solid var(--primary);\n  background: white;\n  color: var(--primary);\n  border-radius: 50px;\n  font-weight: 600;\n  cursor: pointer;\n  transition: all 0.3s ease;\n}\n\n.wp_blog_code-tab-button:hover {\n  background: var(--secondary);\n}\n\n.wp_blog_code-tab-button.active {\n  background: var(--primary);\n  color: white;\n}\n\n\/* Code Content *\/\n.wp_blog_code-tab-content {\n  display: none;\n  background: var(--code-bg);\n  border-radius: var(--tab-radius);\n}\n\n.wp_blog_code-tab-content.active {\n  display: block;\n}\n\n.wp_blog_code-tab-content pre {\n  margin: 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\n\/* Dark mode variables *\/\n.wp_blog_theme.dark-mode {\n  --light-bg: #121212;\n  --text-dark: #f5f5f5;\n  --shadow: 0 4px 12px rgba(255, 255, 255, 0.08);\n  --code-bg: #1e1e1e;\n  --code-text: #c5f0ff;\n}\n\n.wp_blog_theme.dark-mode .wp_blog_explanation {\n  background: #1e1e1e;\n}\n\n\/* Dark mode code highlight *\/\n.wp_blog_theme.dark-mode .wp_blog_explanation code {\n  background: #333;\n  color: #ffd27f;\n}\n\n.wp_blog_theme {\n  position: relative; \/* makes it the reference for absolute children *\/\n}\n\n.wp_blog_toggle-btn {\n  position: absolute;\n  top: 1rem;\n  right: 1rem;\n  z-index: 9999;\n  padding: 0.5rem 0.8rem;\n  border-radius: 10%;\n  background: var(--primary);\n  color: white;\n  font-weight: bold;\n  cursor: pointer;\n  border: none;\n  box-shadow: var(--shadow);\n  transition: background 0.3s, transform 0.2s;\n}\n\n.wp_blog_toggle-btn:hover {\n  background: #cc772e;\n}\n\n.wp_blog_theme.dark-mode .wp_blog_code-tabs-container {\n  background: #1e1e1e;\n}\n<\/style>\n\n<div class=\"wp_blog_container wp_blog_theme\"> \n    <button id=\"blogNotesThemeToggle\" class=\"wp_blog_toggle-btn\">\ud83c\udf19<\/button>\n    <h1 class=\"wp_blog_main-heading\"><\/h1>\n    <div class=\"wp_blog_explanation\">\n        <h2>Problem Statement:<\/h2>\n\n        <p>Write a function that reverses a string. The input string is given as an array of characters <code>s<\/code>. You must do this by modifying the input array in-place with <code>O(1)<\/code>extra memory.<\/p>\n\n                <h2>Examples:<\/h2>\n\n                <h5>Example 1:<\/h5>\n                <p><strong>Input:<\/strong>s = [&#8220;h&#8221;,&#8221;e&#8221;,&#8221;l&#8221;,&#8221;l&#8221;,&#8221;o&#8221;]<\/p>\n                <p><strong>Output:<\/strong>[&#8220;o&#8221;,&#8221;l&#8221;,&#8221;l&#8221;,&#8221;e&#8221;,&#8221;h&#8221;]<\/p>\n\n                <h5>Example 2:<\/h5>\n                <p><strong>Input:<\/strong>s = [&#8220;H&#8221;,&#8221;a&#8221;,&#8221;n&#8221;,&#8221;n&#8221;,&#8221;a&#8221;,&#8221;h&#8221;]<\/p>\n                <p><strong>Output:<\/strong>[&#8220;h&#8221;,&#8221;a&#8221;,&#8221;n&#8221;,&#8221;n&#8221;,&#8221;a&#8221;,&#8221;H&#8221;]<\/p>\n                <h2>Approach: Two Pointer Technique<\/h2>\n                <ul>\n                    <li>Initialize two pointers, one at the start and one at the end of the array.<\/li>\n                    <li>Swap the characters at both pointers.<\/li>\n                    <li>Move the pointers towards the center until they meet.<\/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(1)<\/strong><\/p>\n                <\/li>\n\n<h2>Dry Run<\/h2>\n<div style=\"background: var(--light-bg); border-left: 4px solid var(--primary); padding: 1rem; border-radius: var(--tab-radius); margin: 1rem 0; color: var(--text-dark);\"> \n  <p><strong>Input:<\/strong> <code>s = [\"h\", \"e\", \"l\", \"l\", \"o\"]<\/code><\/p> \n  \n  <pre style=\"white-space: pre-wrap; background: var(--code-bg); padding: 1rem; border-radius: 8px; overflow-x: auto; color: var(--code-text);\">\nlen = 5, halfLen = 2\n                    \ni = 0 \u2192 swap s[0] and s[4] \u2192 [\"o\", \"e\", \"l\", \"l\", \"h\"]\ni = 1 \u2192 swap s[1] and s[3] \u2192 [\"o\", \"l\", \"l\", \"e\", \"h\"]\n  <\/pre> \n  \n  <p><strong>Output:<\/strong> <code>[\"o\", \"l\", \"l\", \"e\", \"h\"]<\/code><\/p> \n<\/div>\n\n                \n        <h2>Visualisation:<\/h2>\n        <img decoding=\"async\" src=\"https:\/\/namastedev.com\/blog\/wp-content\/uploads\/2025\/06\/Screenshot-2025-06-26-at-8.19.31\u202fPM.png\" alt=\"Reverse String\" \/>\n    <\/div>\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 reverseString = function(s) {\n    let len = s.length;\n    let halfLen = Math.floor(len \/ 2);\n\n    for (let i = 0; i < halfLen; i++) {\n        let temp = s[i];\n        s[i] = s[len - i - 1];\n        s[len - i - 1] = temp;\n    }\n};\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\">\nclass Solution(object):\n    def reverseString(self, s):\n        left, right = 0, len(s) - 1\n        while left < right:\n            s[left], s[right] = s[right], s[left]\n            left += 1\n            right -= 1\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 class Solution {\n    public void reverseString(char[] s) {\n        int left = 0, right = s.length - 1;\n        while (left < right) {\n            char temp = s[left];\n            s[left] = s[right];\n            s[right] = temp;\n            left++;\n            right--;\n        }\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\">\nclass Solution {\npublic:\n    void reverseString(vector<char>& s) {\n        int left = 0, right = s.size() - 1;\n        while (left < right) {\n            swap(s[left], s[right]);\n            left++;\n            right--;\n        }\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\">\nvoid reverseString(char* s, int sSize) {\n    int left = 0, right = sSize - 1;\n    while (left < right) {\n        char temp = s[left];\n        s[left] = s[right];\n        s[right] = temp;\n        left++;\n        right--;\n    }\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 class Solution {\n    public void ReverseString(char[] s) {\n        int left = 0, right = s.Length - 1;\n        while (left < right) {\n            char temp = s[left];\n            s[left] = s[right];\n            s[right] = temp;\n            left++;\n            right--;\n        }\n    }\n}          <\/code><\/pre>\n        <\/div>\n    <\/div>\n<\/div>\n\n<script>\ndocument.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) => content.classList.remove(\"active\"));\n\n      button.classList.add(\"active\");\n      document\n        .querySelector(`.wp_blog_code-tab-content[data-lang=\"${lang}\"]`)\n        .classList.add(\"active\");\n    });\n  });\n\n  const themeToggle = document.getElementById(\"blogNotesThemeToggle\");\n  const themeContainer = document.querySelector(\".wp_blog_theme\");\n\n  themeToggle.addEventListener(\"click\", () => {\n    themeContainer.classList.toggle(\"dark-mode\");\n    themeToggle.textContent =\n      themeContainer.classList.contains(\"dark-mode\") ? \"\u2600\ufe0f\" : \"\ud83c\udf19\";\n  });\n});\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>\ud83c\udf19 Problem Statement: Write a function that reverses a string. The input string is given as an array of characters s. You must do this by modifying the input array in-place with O(1)extra memory. Examples: Example 1: Input:s = [&#8220;h&#8221;,&#8221;e&#8221;,&#8221;l&#8221;,&#8221;l&#8221;,&#8221;o&#8221;] Output:[&#8220;o&#8221;,&#8221;l&#8221;,&#8221;l&#8221;,&#8221;e&#8221;,&#8221;h&#8221;] Example 2: Input:s = [&#8220;H&#8221;,&#8221;a&#8221;,&#8221;n&#8221;,&#8221;n&#8221;,&#8221;a&#8221;,&#8221;h&#8221;] Output:[&#8220;h&#8221;,&#8221;a&#8221;,&#8221;n&#8221;,&#8221;n&#8221;,&#8221;a&#8221;,&#8221;H&#8221;] Approach: Two Pointer Technique Initialize two pointers, one<\/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":[322,260,176,175,211,811,810,174,172,311,173,284],"tags":[],"class_list":["post-7280","post","type-post","status-publish","format-standard","category-algorithms-and-data-structures","category-c-c-plus-plus","category-csharp","category-cplusplus","category-data-structures","category-data-structures-and-algorithms","category-dsa","category-java","category-javascript","category-namastedev-community","category-python","category-software-engineering"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/7280","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=7280"}],"version-history":[{"count":4,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/7280\/revisions"}],"predecessor-version":[{"id":10158,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/7280\/revisions\/10158"}],"wp:attachment":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/media?parent=7280"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/categories?post=7280"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/tags?post=7280"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}