Create Dijkstra's Algorithm.cpp

Author: MohammedHamzaMalik

Competitive-Programming/Graph II/Dijkstra's Algorithm.cpp

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+/*
+Dijkstra's Algorithm
+Send Feedback
+Given an undirected, connected and weighted graph G(V, E) with V number of vertices (which are numbered from 0 to V-1) and E number of edges.
+Find and print the shortest distance from the source vertex (i.e. Vertex 0) to all other vertices (including source vertex also) using Dijkstra's Algorithm.
+Print the ith vertex number and the distance from source in one line separated by space. Print different vertices in different lines.
+Note : Order of vertices in output doesn't matter.
+Input Format :
+First line will contain T(number of test case), each test case follows as.
+Line 1: Two Integers V and E (separated by space)
+Next E lines : Three integers ei, ej and wi, denoting that there exists an edge between vertex ei and vertex ej with weight wi (separated by space)
+Output Format :
+In different lines, ith vertex number and its distance from source (separated by space)
+Constraints :
+1 <= T <= 10
+2 <= V, E <= 10^3
+Sample Input 1 :
+1
+4 4
+0 1 3
+0 3 5
+1 2 1
+2 3 8
+Sample Output 1 :
+0 0
+1 3
+2 4
+3 5
+*/
+
+
+
+#include<iostream>
+#include<climits>
+#include<algorithm>
+using namespace std;
+void algo(int** arr, int v, int e, bool* visited, int* dist, int current_vertex)
+{
+	for (int i = 0; i < v - 1; i++)
+	{
+		int vertex_with_minimum_distance=-1;
+		int min_distance = INT_MAX;
+		for (int j = 0; j < v; j++)
+		{
+			if (!visited[j] && min_distance > dist[j])
+			{
+				min_distance = dist[j];
+				vertex_with_minimum_distance = j;
+			}
+		}
+
+		visited[vertex_with_minimum_distance] = true;
+		for (int j = 0; j < v; j++)
+		{
+			if (!visited[j] && dist[j] > dist[vertex_with_minimum_distance] + arr[vertex_with_minimum_distance][j] && arr[vertex_with_minimum_distance][j] > 0)
+			{
+				dist[j] = dist[vertex_with_minimum_distance] + arr[vertex_with_minimum_distance][j];
+			}
+		}
+	}
+}
+int main()
+{
+	int t;cin>>t;
+    while(t--){
+        int v, e;
+	cin >> v >> e;
+	int** arr = new int*[v];
+	for (int i = 0; i < v; i++)
+	{
+		arr[i] = new int[v];
+		for (int j = 0; j < v; j++)
+		{
+			arr[i][j] = 0;
+		}
+	}
+	for (int i = 0; i < e; i++)
+	{
+		int v1, v2, w;
+		cin >> v1 >> v2 >> w;
+		arr[v1][v2] = w;
+		arr[v2][v1] = w;
+	}
+	bool* visited = new bool[v];
+	for (int i = 0; i < v; i++)
+	{
+		visited[i] = false;
+	}
+	int* dist = new int[v];
+	for (int i = 0; i < v; i++)
+	{
+		dist[i] = INT_MAX;
+	}
+	dist[0] = 0;
+	algo(arr, v, e, visited, dist, 0);
+	for (int i = 0; i < v; i++)
+	{
+		cout << i << " " << dist[i] << endl;
+	}
+    }
+}