{"id":11320,"date":"2025-12-16T16:39:44","date_gmt":"2025-12-16T11:09:44","guid":{"rendered":"https:\/\/namastedev.com\/blog\/?p=11320"},"modified":"2026-01-11T19:30:28","modified_gmt":"2026-01-11T14:00:28","slug":"dijkstras-algorithm-code","status":"publish","type":"post","link":"https:\/\/namastedev.com\/blog\/dijkstras-algorithm-code\/","title":{"rendered":"Dijkstra Algorithm Code"},"content":{"rendered":"\n<!-- Shortest Path in unweighted graph -->\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 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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>Dijkstra&#8217;s Algorithm<\/h2>\n    <h2>Code<\/h2>\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    <div class=\"wp_blog_code-tab-content active\" data-lang=\"js\">\n    <pre>\n  class MinHeap {\n            constructor() {\n              this.heap = [];\n            }\n\n            parent(i) { return Math.floor((i - 1) \/ 2); }\n            left(i) { return 2 * i + 1; }\n            right(i) { return 2 * i + 2; }\n\n            size() {\n              return this.heap.length;\n            }\n\n            swap(i, j) {\n              [this.heap[i], this.heap[j]] = [this.heap[j], \n              this.heap[i]];\n            }\n\n            push(pair) {\n              this.heap.push(pair);\n              this.heapifyUp();\n            }\n\n            heapifyUp() {\n              let i = this.heap.length - 1;\n              while (i > 0 && this.heap[i][0]  \n              this.heap[this.parent(i)][0]) {\n                this.swap(i, this.parent(i));\n                i = this.parent(i);\n              }\n            }\n\n            pop() {\n              if (this.heap.length === 0) return null;\n              if (this.heap.length === 1) return this.heap.pop();\n\n              const root = this.heap[0];\n              this.heap[0] = this.heap.pop();\n              this.heapifyDown();\n              return root;\n            }\n\n            heapifyDown() {\n              let i = 0;\n              while (true) {\n                let smallest = i;\n                let left = this.left(i);\n                let right = this.right(i);\n\n                if (left < this.heap.length &#038;&#038; this.heap[left][0] \n                < this.heap[smallest][0]) {\n                  smallest = left;\n                }\n                if (right < this.heap.length &#038;&#038; this.heap[right][0] \n                < this.heap[smallest][0]) {\n                  smallest = right;\n                }\n\n                if (smallest !== i) {\n                  this.swap(i, smallest);\n                  i = smallest;\n                } else {\n                  break;\n                }\n              }\n            }\n          }\n\n          function dijkstras(graph, src) {\n            let n = graph.length;\n            let dist = new Array(n).fill(Infinity);\n            dist[src] = 0;\n\n            let pq = new MinHeap();\n            pq.push([0, src]); \/\/ [distance, node]\n\n            while (pq.size()) {\n              let [nodeDist, node] = pq.pop();\n\n              if (nodeDist > dist[node]) continue;\n\n              for (let [neighbor, weight] of graph[node]) {\n                let newDist = dist[node] + weight;\n                if (newDist < dist[neighbor]) {\n                  dist[neighbor] = newDist;\n                  pq.push([newDist, neighbor]);\n                }\n              }\n            }\n            return dist;\n          }\n\n          const graph = [\n          [[1, 2], [2, 4]],\n          [[3, 7], [2, 1]], \n          [[4, 3], [5, 1]],\n          [[6, 1]],\n          [[3, 2], [6, 5]], \n          [[3, 3], [6, 8]],\n          []\n      ];\n      console.log(dijkstras(graph, 0));\n    <\/pre>\n    <\/div>\n     <div class=\"wp_blog_code-tab-content\" data-lang=\"py\">\n      <pre>\nimport heapq\n\ndef dijkstras(graph, src):\n    n = len(graph)\n    dist = [float('inf')] * n\n    dist[src] = 0\n\n    pq = []\n    heapq.heappush(pq, (0, src))  # (distance, node)\n\n    while pq:\n        node_dist, node = heapq.heappop(pq)\n\n        if node_dist > dist[node]:\n            continue\n\n        for neighbor, weight in graph[node]:\n            new_dist = dist[node] + weight\n            if new_dist < dist[neighbor]:\n                dist[neighbor] = new_dist\n                heapq.heappush(pq, (new_dist, neighbor))\n\n    return dist\n\n\ngraph = [\n    [(1, 2), (2, 4)],\n    [(3, 7), (2, 1)],\n    [(4, 3), (5, 1)],\n    [(6, 1)],\n    [(3, 2), (6, 5)],\n    [(3, 3), (6, 8)],\n    []\n]\n\nprint(dijkstras(graph, 0))\n\n    <\/pre>\n    <\/div>\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"java\">\n      <pre>\nimport java.util.*;\n\nclass Solution {\n    static int[] shortestDistance(List<List<Integer>> graph, int src) {\n        int n = graph.size();\n        int[] dist = new int[n];\n        Arrays.fill(dist, Integer.MAX_VALUE);\n        dist[src] = 0;\n\n        Queue<Integer> q = new LinkedList<>();\n        q.add(src);\n\n        while (!q.isEmpty()) {\n            int curr = q.poll();\n            for (int neighbor : graph.get(curr)) {\n                if (dist[neighbor] == Integer.MAX_VALUE) {\n                    dist[neighbor] = dist[curr] + 1;\n                    q.add(neighbor);\n                }\n            }\n        }\n        return dist;\n    }\n\n    public static void main(String[] args) {\n        List<List<Integer>> graph = new ArrayList<>();\n\n        graph.add(Arrays.asList(1, 2));\n        graph.add(Arrays.asList(3));\n        graph.add(Arrays.asList(4));\n        graph.add(Arrays.asList(5));\n        graph.add(Arrays.asList(3));\n        graph.add(new ArrayList<>());\n\n        System.out.println(Arrays.toString(shortestDistance(graph, 0)));\n    }\n}\n  <\/pre>\n    <\/div>\n\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"cpp\">\n      <pre>\n#include &lt;bits\/stdc++.h&gt;\nusing namespace std;\n\nvector<int> dijkstras(vector<vector<pair<int,int>>>& graph, int src) {\n    int n = graph.size();\n    vector<int> dist(n, INT_MAX);\n    dist[src] = 0;\n\n    priority_queue<pair<int,int>,\n        vector<pair<int,int>>,\n        greater<pair<int,int>>> pq;\n\n    pq.push({0, src});\n\n    while (!pq.empty()) {\n        auto [nodeDist, node] = pq.top();\n        pq.pop();\n\n        if (nodeDist > dist[node]) continue;\n\n        for (auto [neighbor, weight] : graph[node]) {\n            int newDist = dist[node] + weight;\n            if (newDist < dist[neighbor]) {\n                dist[neighbor] = newDist;\n                pq.push({newDist, neighbor});\n            }\n        }\n    }\n    return dist;\n}\n\nint main() {\n    vector<vector<pair<int,int>>> graph(7);\n\n    graph[0] = {{1,2},{2,4}};\n    graph[1] = {{3,7},{2,1}};\n    graph[2] = {{4,3},{5,1}};\n    graph[3] = {{6,1}};\n    graph[4] = {{3,2},{6,5}};\n    graph[5] = {{3,3},{6,8}};\n\n    vector<int> res = dijkstras(graph, 0);\n    for (int x : res) cout << x << \" \";\n}\n<\/pre>\n    <\/div>\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"c\">\n      <pre>\n#include &lt;stdio.h&gt;\n#include &lt;limits.h&gt;\n\n#define V 7\n#define E 12\n\ntypedef struct {\n    int node, dist;\n} HeapNode;\n\nHeapNode heap[100];\nint heapSize = 0;\n\nvoid swap(int i, int j) {\n    HeapNode temp = heap[i];\n    heap[i] = heap[j];\n    heap[j] = temp;\n}\n\nvoid push(int node, int dist) {\n    heap[heapSize++] = (HeapNode){node, dist};\n    int i = heapSize - 1;\n\n    while (i > 0 && heap[(i - 1) \/ 2].dist > heap[i].dist) {\n        swap(i, (i - 1) \/ 2);\n        i = (i - 1) \/ 2;\n    }\n}\n\nHeapNode pop() {\n    HeapNode root = heap[0];\n    heap[0] = heap[--heapSize];\n\n    int i = 0;\n    while (1) {\n        int smallest = i;\n        int l = 2*i + 1, r = 2*i + 2;\n\n        if (l < heapSize &#038;&#038; heap[l].dist < heap[smallest].dist)\n            smallest = l;\n        if (r < heapSize &#038;&#038; heap[r].dist < heap[smallest].dist)\n            smallest = r;\n\n        if (smallest == i) break;\n        swap(i, smallest);\n        i = smallest;\n    }\n    return root;\n}\n\nint main() {\n    int graph[V][V] = {\n        {0,2,4,0,0,0,0},\n        {0,0,1,7,0,0,0},\n        {0,0,0,0,3,1,0},\n        {0,0,0,0,0,0,1},\n        {0,0,0,2,0,0,5},\n        {0,0,0,3,0,0,8},\n        {0,0,0,0,0,0,0}\n    };\n\n    int dist[V];\n    for (int i = 0; i < V; i++) dist[i] = INT_MAX;\n    dist[0] = 0;\n\n    push(0, 0);\n\n    while (heapSize) {\n        HeapNode curr = pop();\n        int u = curr.node;\n\n        for (int v = 0; v < V; v++) {\n            if (graph[u][v] &#038;&#038; dist[u] + graph[u][v] < dist[v]) {\n                dist[v] = dist[u] + graph[u][v];\n                push(v, dist[v]);\n            }\n        }\n    }\n\n    for (int i = 0; i < V; i++)\n        printf(\"%d \", dist[i]);\n\n    return 0;\n}\n<\/pre>\n    <\/div>\n\n    <div class=\"wp_blog_code-tab-content\" data-lang=\"cs\">\n    <pre>\nusing System;\nusing System.Collections.Generic;\n\nclass Solution {\n    static int[] Dijkstras(List<(int,int)>[] graph, int src) {\n        int n = graph.Length;\n        int[] dist = new int[n];\n        Array.Fill(dist, int.MaxValue);\n        dist[src] = 0;\n\n        var pq = new PriorityQueue<int, int>();\n        pq.Enqueue(src, 0);\n\n        while (pq.Count > 0) {\n            pq.TryDequeue(out int node, out int nodeDist);\n\n            if (nodeDist > dist[node]) continue;\n\n            foreach (var (neighbor, weight) in graph[node]) {\n                int newDist = dist[node] + weight;\n                if (newDist < dist[neighbor]) {\n                    dist[neighbor] = newDist;\n                    pq.Enqueue(neighbor, newDist);\n                }\n            }\n        }\n        return dist;\n    }\n\n    static void Main() {\n        var graph = new List<(int,int)>[7];\n        for (int i = 0; i < 7; i++) graph[i] = new();\n\n        graph[0].Add((1,2));\n        graph[0].Add((2,4));\n        graph[1].Add((3,7));\n        graph[1].Add((2,1));\n        graph[2].Add((4,3));\n        graph[2].Add((5,1));\n        graph[3].Add((6,1));\n        graph[4].Add((3,2));\n        graph[4].Add((6,5));\n        graph[5].Add((3,3));\n        graph[5].Add((6,8));\n\n        Console.WriteLine(string.Join(\" \", Dijkstras(graph, 0)));\n    }\n}\n<\/pre>\n    <\/div>\n  <\/div>\n<\/div>  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