{"id":10096,"date":"2025-09-22T20:45:57","date_gmt":"2025-09-22T15:15:57","guid":{"rendered":"https:\/\/namastedev.com\/blog\/?p=10096"},"modified":"2025-09-23T21:04:02","modified_gmt":"2025-09-23T15:34:02","slug":"car-pooling","status":"publish","type":"post","link":"https:\/\/namastedev.com\/blog\/car-pooling\/","title":{"rendered":"Car Pooling"},"content":{"rendered":"\n\n<!-- merge_7-->\n<!-- PrismJS for Syntax Highlighting -->\n<link href=\"https:\/\/cdn.jsdelivr.net\/npm\/prismjs@1.29.0\/themes\/prism-tomorrow.min.css\" rel=\"stylesheet\">\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\n  <div class=\"wp_blog_explanation\">\n    <h2>Problem Statement:<\/h2>\n    <p>\n        There is a car with <code>capacity<\/code> empty seats. The vehicle only drives east (i.e., it cannot turn around and drive west).    \n    <\/p> \n    <p>\n        You are given the integer <code>capacity<\/code> and an array <code>trips<\/code> where <code>trips[i] = [numPassengers<sub>i<\/sub>, from<sub>i<\/sub>, to<sub>i<\/sub>]<\/code> indicates that the i<sup>th<\/sup> trip has <code>numPassengers<sub>i<\/sub><\/code> passengers and the locations to pick them up and drop them off are <code>from<sub>i<\/sub><\/code> and <code>to<sub>i<\/sub><\/code> respectively. The locations are given as the number of kilometers due east from the car&#8217;s initial location.\n    <\/p>\n\n    <p>\n        Return <code>true<\/code> if it is possible to pick up and drop off all passengers for all the given trips, or <code>false<\/code> otherwise.\n    <\/p>\n\n    <h3>Example 1:<\/h2>\n    <p><strong>Input:<\/strong> trips = [[2,1,5],[3,3,7]], capacity = 4<\/p>\n    <p><strong>Output:<\/strong> false<\/p>\n\n    <h3>Example 2:<\/h2>\n    <p><strong>Input:<\/strong> trips = [[2,1,5],[3,3,7]], capacity = 5<\/p>\n    <p><strong>Output:<\/strong> true<\/p>\n\n    <!-- <h3>Example 3:<\/h3>\n    <p><strong>Input: <\/strong>intervals = [[1,2],[2,3]]<\/p>\n    <p><strong>Output: <\/strong>0<\/p>\n    <p><strong>Explanation: <\/strong>\n       You don't need to remove any of the intervals since they're already non-overlapping.\n    <\/p> -->\n\n    <h3>Constraints<\/h3>\n    <ul>\n        <li><code>1 <= trips.length <= 1000<\/code><\/li>\n        <li><code>trips[i].length == 3<\/sup><\/code><\/li>\n        <li><code>1 <= numPassengersi <= 100<\/code><\/li>\n        <li><code>0 <= fromi < toi <= 1000<\/code><\/li>\n        <li><code>1 <= capacity <= 10<sup>5<\/sup><\/code><\/li>\n    <\/ul>\n    \n<h2>Approach:<\/h2>\n   <ul>\n    <li>Create an array <code>loc[1001] <\/code> to track passenger changes at each location.\n      <ul>\n        <li>At pickup point <strong>from<\/strong>, add <strong>+passengers<\/strong>.<\/li>\n        <li>At drop point <strong>to<\/strong>, subtract <strong>-passengers<\/strong>.<\/li>\n      <\/ul>\n    <\/li>\n    <li>\n      Traverse <code>loc<\/code> while maintaining <code>usedCapacity<\/code>.\n      <ul>\n        <li>Keep <strong>adding changes<\/strong> at each location.<\/li>\n        <li>If <code>usedCapacity<\/code> ever exceeds <code>carCapacity<\/code>, return <strong>false<\/strong>.<\/li>\n      <\/ul>\n    <\/li>\n\n    <li>If the loop completes without exceeding capacity, <strong>return true<\/strong>.<\/li>\n\n   <\/ul>\n\n    <h2>Time & Space Complexity:<\/h2>\n    <p><strong>Time Complexity:<\/strong> <code>O(n)<\/code><\/p>\n    <p><strong>Space Complexity:<\/strong> <code>O(1)<\/code><\/p>\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>arr = [[2,1,5],[3,3,7]], carCapacity = 4<\/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);\">\n\nStep 0: Start Function: carPooling(arr, carCapacity)\narr = [[2,1,5], [3,3,7]]\ncarCapacity = 4\nloc = Array(1001).fill(0)\nusedCapacity = 0\n\nStep 1: Process trips\nIteration (i = 0): arr[0] = [2,1,5]\n- passengers = 2, from = 1, to = 5\n- loc[1] = loc[1] + 2 \u2192 loc[1] = 2\n- loc[5] = loc[5] - 2 \u2192 loc[5] = -2\n\nIteration (i = 1): arr[1] = [3,3,7]\n- passengers = 3, from = 3, to = 7\n- loc[3] = loc[3] + 3 \u2192 loc[3] = 3\n- loc[7] = loc[7] - 3 \u2192 loc[7] = -3\n\nFinal loc changes (only relevant indices):\nloc[1] = 2, loc[3] = 3, loc[5] = -2, loc[7] = -3\n\nStep 2: Iterate over loc to check capacity\ni = 0: usedCapacity = 0 + loc[0] = 0  \ni = 1: usedCapacity = 0 + 2 = 2 \u2192 (\u2264 4, OK)  \ni = 2: usedCapacity = 2 + 0 = 2 \u2192 (\u2264 4, OK)  \ni = 3: usedCapacity = 2 + 3 = 5 \u2192 (> 4, exceeds capacity)  \n\nCondition triggered \u2192 return false\n\nStep 3: End\nFunction returns false because at i = 3, usedCapacity exceeded carCapacity\n  <\/pre> \n  \n  <p><strong>Output:<\/strong> <code>false<\/code><\/p> \n<\/div>\n\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    <div class=\"wp_blog_code-tab-content active\" data-lang=\"js\">\n      <pre><code class=\"language-javascript\">\nvar carPooling = function(trips, carCapacity) {\n    let loc = Array(1001).fill(0);\n    for (let i = 0; i < trips.length; i++) {\n        let [passengers, from, to] = trips[i];\n        loc[from] += passengers;   \/\/ Pick up passengers\n        loc[to] -= passengers;     \/\/ Drop off passengers\n    }\n    let usedCapacity = 0;\n    for (let i = 0; i < 1001; i++) {\n        usedCapacity += loc[i];\n        if (usedCapacity > carCapacity) {\n            return false; \n        }\n    }\n    return true; \n};\n<\/code><\/pre>\n    <\/div>\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"py\">\n      <pre><code class=\"language-python\">\ndef carPooling(trips, capacity):\n    loc = [0] * 1001\n    for passengers, frm, to in trips:\n        loc[frm] += passengers\n        loc[to] -= passengers\n\n    used_capacity = 0\n    for x in loc:\n        used_capacity += x\n        if used_capacity > capacity:\n            return False\n    return True\n      <\/code><\/pre>\n    <\/div>\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"java\">\n      <pre><code class=\"language-java\">\nclass Solution {\n    public boolean carPooling(int[][] trips, int capacity) {\n        int[] loc = new int[1001];\n        for (int i = 0; i < trips.length; i++) {\n            int passengers = trips[i][0];\n            int from = trips[i][1];\n            int to = trips[i][2];\n            loc[from] += passengers;\n            loc[to] -= passengers;\n        }\n        int usedCapacity = 0;\n        for (int i = 0; i < loc.length; i++) {\n            usedCapacity += loc[i];\n            if (usedCapacity > capacity) return false;\n        }\n        return true;\n    }\n}\n    <\/code><\/pre>\n    <\/div>\n\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"cpp\">\n      <pre><code class=\"language-cpp\">\n<!-- #include &lt;vector&gt; -->\n#include &lt;vector&gt;\nusing namespace std;\n\nclass Solution {\npublic:\n    bool carPooling(vector<vector<int>>& trips, int capacity) {\n        vector<int> loc(1001, 0);\n        for (const auto &t : trips) {\n            int passengers = t[0];\n            int from = t[1];\n            int to = t[2];\n            loc[from] += passengers;\n            loc[to] -= passengers;\n        }\n        int usedCapacity = 0;\n        for (int x : loc) {\n            usedCapacity += x;\n            if (usedCapacity > capacity) return false;\n        }\n        return true;\n    }\n};\n<\/code><\/pre>\n    <\/div>\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;\n#include &lt;stddef.h&gt;\n\nbool carPooling(int trips[][3], size_t tripsSize, int capacity) {\n    int loc[1001];\n    memset(loc, 0, sizeof(loc));\n    for (size_t i = 0; i < tripsSize; ++i) {\n        int passengers = trips[i][0];\n        int from = trips[i][1];\n        int to = trips[i][2];\n        loc[from] += passengers;\n        loc[to] -= passengers;\n    }\n    int usedCapacity = 0;\n    for (int i = 0; i < 1001; ++i) {\n        usedCapacity += loc[i];\n        if (usedCapacity > capacity) return false;\n    }\n    return true;\n}\n <\/code><\/pre>\n    <\/div>\n\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"cs\">\n      <pre><code class=\"language-csharp\">\nusing System;\npublic class Solution {\n    public bool CarPooling(int[][] trips, int capacity) {\n        int[] loc = new int[1001];\n        for (int i = 0; i < trips.Length; i++) {\n            int passengers = trips[i][0];\n            int from = trips[i][1];\n            int to = trips[i][2];\n            loc[from] += passengers;\n            loc[to] -= passengers;\n        }\n\n        int usedCapacity = 0;\n        for (int i = 0; i < loc.Length; i++) {\n            usedCapacity += loc[i];\n            if (usedCapacity > capacity) return false;\n        }\n        return true;\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\n","protected":false},"excerpt":{"rendered":"<p>\ud83c\udf19 Problem Statement: There is a car with capacity empty seats. The vehicle only drives east (i.e., it cannot turn around and drive west). You are given the integer capacity and an array trips where trips[i] = [numPassengersi, fromi, toi] indicates that the ith trip has numPassengersi passengers and the locations to pick them up<\/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":[210,322,260,176,175,211,811,810,172,180,173],"tags":[],"class_list":["post-10096","post","type-post","status-publish","format-standard","category-algorithms","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-javascript","category-kotlin","category-python"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/10096","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=10096"}],"version-history":[{"count":2,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/10096\/revisions"}],"predecessor-version":[{"id":10104,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/posts\/10096\/revisions\/10104"}],"wp:attachment":[{"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/media?parent=10096"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/categories?post=10096"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/namastedev.com\/blog\/wp-json\/wp\/v2\/tags?post=10096"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}