{"id":7898,"date":"2025-07-15T18:12:38","date_gmt":"2025-07-15T12:42:38","guid":{"rendered":"https:\/\/namastedev.com\/blog\/?p=7898"},"modified":"2025-07-15T18:14:04","modified_gmt":"2025-07-15T12:44:04","slug":"is-subsequence","status":"publish","type":"post","link":"https:\/\/namastedev.com\/blog\/is-subsequence\/","title":{"rendered":"Is subsequence"},"content":{"rendered":"\n<!-- Is Subsequence -->\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    --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    \/* 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    .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    .wp_blog_explanation code {\n        background: #fef9f4;\n        padding: 3px 6px;\n        border-radius: 4px;\n        font-family: \"Courier New\", monospace;\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    .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    .wp_blog_code-tab-button:hover {\n        background: var(--secondary);\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    .wp_blog_code-tab-content.active {\n        display: block;\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<\/style>\n\n<div class=\"wp_blog_container wp_blog_theme\">\n<h1 class=\"wp_blog_main-heading\"><\/h1>\n\n<div class=\"wp_blog_explanation\">\n    <h2>Problem Statement:<\/h2>\n    <p>\n        Given two strings <code>s<\/code> and <code>t<\/code>, return true if s is a <strong>subsequence<\/strong> of <code>t<\/code>, or <code>false<\/code> otherwise.\n    <\/p>\n    <p> A <strong>subsequence<\/strong> of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., <code>\"ace\"<\/code> is a subsequence of <code>\"abcde\"<\/code> while <code>\"aec\"<\/code> is not). \n    <\/p>\n    <h2>Examples:<\/h2>\n    <p><strong>Example 1:<\/strong><\/p>\n    <p><strong>Input:<\/strong> s = &#8220;abc&#8221;, t = &#8220;ahbgdc&#8221;<\/p> \n    <p><strong>Output:<\/strong><code> true<\/code><\/p>\n\n    <p><strong>Example 2:<\/strong><\/p>\n    <p><strong>Input:<\/strong> s = &#8220;axc&#8221;, t = &#8220;ahbgdc&#8221;<\/p> \n    <p><strong>Output:<\/strong><code> false<\/code><\/p>\n\n    \n\n    <h2>Constraints:<\/h2>\n    <ul>\n        <li><code>0 <= s.length <= 100<\/code><\/li>\n        <li><code>0 <= t.length <= 10<sup>4<\/sup><\/code><\/li>\n        <li><code>s<\/code> and <code>t<\/code> consist only of lowercase English letters.<\/li>\n    <\/ul>\n\n    <h2>Approach:<\/h2>\n    <ul>\n        <li>Use two pointers <code>i<\/code> (for string <code>s<\/code>) and <code>j<\/code> (for string <code>t<\/code>).<\/li>\n        <li>Traverse through <code>t<\/code> using <code>j<\/code>.<\/li>\n        <li>If characters match <code>(s[i] === t[j])<\/code>, move <code>i<\/code> to the next character.<\/li>\n        <li>Always move <code>j<\/code><\/li>\n        <li>If <code>i<\/code> reaches the end of <code>s<\/code>, it means all characters of <code>s<\/code> are found in <code>t<\/code> in order.<\/li>\n        <li><strong>Return<\/strong> true if i === s.length, else false.<\/li>\n    <\/ul>\n\n    <h2>Visualisation:<\/h2>\n    <img decoding=\"async\"\n        src=\"https:\/\/namastedev.com\/blog\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-15-at-6.10.58\u202fPM.png\"\n        alt=\"stack\"\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> \n                <\/p>\n                <\/li>\n\n<h2>Dry Run<\/h2> <div style=\"background: #f9f9f9; border-left: 4px solid var(--primary); padding: 1rem; border-radius: var(--tab-radius); margin: 1rem 0;\"> <p><strong>Input:<\/strong><\/p> <pre style=\"white-space: pre-wrap; background: #fff5ea; padding: 1rem; border-radius: 8px; overflow-x: auto;\"> s = \"abc\", t = \"ahbgdc\" <\/pre> <p><strong>State Transitions:<\/strong><\/p> <pre style=\"white-space: pre-wrap; background: #fff5ea; padding: 1rem; border-radius: 8px; overflow-x: auto;\"> Note: This is a two-pointer approach checking if string `s` is a subsequence of `t`.\nStep 1: Initialize\n\u2192 i = 0, j = 0\n\u2192 s[i] = 'a', t[j] = 'a' \u2192 match \u2192 increment i \u2192 i = 1\n\u2192 increment j \u2192 j = 1\n\nStep 2:\n\u2192 s[i] = 'b', t[j] = 'h' \u2192 no match\n\u2192 increment j \u2192 j = 2\n\nStep 3:\n\u2192 s[i] = 'b', t[j] = 'b' \u2192 match \u2192 increment i \u2192 i = 2\n\u2192 increment j \u2192 j = 3\n\nStep 4:\n\u2192 s[i] = 'c', t[j] = 'g' \u2192 no match\n\u2192 increment j \u2192 j = 4\n\nStep 5:\n\u2192 s[i] = 'c', t[j] = 'd' \u2192 no match\n\u2192 increment j \u2192 j = 5\n\nStep 6:\n\u2192 s[i] = 'c', t[j] = 'c' \u2192 match \u2192 increment i \u2192 i = 3\n\u2192 increment j \u2192 j = 6 (loop ends, as j == t.length)\n\n<\/pre> <p><strong>Final Output:<\/strong> <code>true<\/code><\/p> <p><strong>Final State:<\/strong> All characters of <code>s<\/code> were found in <code>t<\/code> in order. Hence, <code>s<\/code> is a subsequence of <code>t<\/code>.<\/p> <\/div>\n\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\">\n            JavaScript\n        <\/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    <div class=\"wp_blog_code-tab-content active\" data-lang=\"js\">\n<pre><code class=\"language-javascript\">\nvar isSubsequence = function(s, t) {\n    let i = j = 0;\n    while(j < t.length) {\n        if(s[i] === t[j]) {\n            ++i\n        } \n        ++j;\n    }\n    return i === s.length;\n};\n<\/code>\n<\/pre>\n<\/div>\n\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"py\">\n        <pre><code class=\"language-python\">\ndef isSubsequence(s, t):\n    i = j = 0\n    while j < len(t):\n        if i < len(s) and s[i] == t[j]:\n            i += 1\n        j += 1\n    return i == len(s)\n    <\/code><\/pre>\n    <\/div>\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"java\">\n        <pre><code class=\"language-java\">\npublic class Solution {\n    public boolean isSubsequence(String s, String t) {\n        int i = 0, j = 0;\n        while (j < t.length()) {\n            if (i < s.length() &#038;&#038; s.charAt(i) == t.charAt(j)) {\n                ++i;\n            }\n            ++j;\n        }\n        return i == s.length();\n    }\n}\n <\/code><\/pre>\n    <\/div>\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"cpp\">\n        <pre><code class=\"language-cpp\">\n#include &lt;string&gt;\nusing namespace std;\n\nbool isSubsequence(string s, string t) {\n    int i = 0, j = 0;\n    while (j < t.length()) {\n        if (s[i] == t[j]) {\n            ++i;\n        }\n        ++j;\n    }\n    return i == s.length();\n}\n<\/code><\/pre>\n    <\/div>\n\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"c\">\n        <pre><code class=\"language-c\">\n#include &lt;stdbool.h&gt;\n#include &lt;string.h&gt;\nbool isSubsequence(char *s, char *t) {\n    int i = 0, j = 0;\n    while (j < strlen(t)) {\n        if (s[i] == t[j]) {\n            ++i;\n        }\n        ++j;\n    }\n    return i == strlen(s);\n}\n<\/code><\/pre>\n    <\/div>\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"cs\">\n        <pre><code class=\"language-csharp\">\npublic class Solution {\n    public bool IsSubsequence(string s, string t) {\n        int i = 0, j = 0;\n        while (j < t.Length) {\n            if (i < s.Length &#038;&#038; s[i] == t[j]) {\n                ++i;\n            }\n            ++j;\n        }\n        return i == s.Length;\n    }\n}\n  <\/code><\/pre>\n    <\/div>\n<\/div>\n<\/div>\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                buttons.forEach((btn) => btn.classList.remove(\"active\"));\n                contents.forEach((content) =>\n                    content.classList.remove(\"active\")\n                );\n                button.classList.add(\"active\");\n                document\n                    .querySelector(\n                        `.wp_blog_code-tab-content[data-lang=\"${lang}\"]`\n                    )\n                    .classList.add(\"active\");\n            });\n        });\n    });\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Problem Statement: Given two strings s and t, return true if s is a subsequence of t, or false otherwise. A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e.,<\/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":[322,260,176,175,212,211,811,810,174,172,173],"tags":[],"class_list":["post-7898","post","type-post","status-publish","format-standard","category-algorithms-and-data-structures","category-c-c-plus-plus","category-csharp","category-cplusplus","category-code-optimization","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\/7898","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=7898"}],"version-history":[{"count":1,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/7898\/revisions"}],"predecessor-version":[{"id":7899,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/7898\/revisions\/7899"}],"wp:attachment":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/media?parent=7898"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/categories?post=7898"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/tags?post=7898"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}