[Algo] floyd warshall algorithm for finding all pair shortest path in a connected graph [CPP]

floyd_warshall_algorithm/CPP/floyd_warshall_algorithm.cpp

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+// Floyd-Warshall Algorithm: all pair shortest path
+#include <iostream>
+#include <climits>
+using namespace std;
+
+#define INF 999999999
+
+int main() {
+	freopen("input.txt", "r", stdin);
+	int i, j, k, n, m;
+	cin >> n >> m;	// number of vertices and edges respectively
+	int graph[n+1][n+1];
+
+	for(i = 1; i <= n; i++) {
+		for(j = 1; j <= n; j++)
+			if(i == j)	graph[i][j] = 0;	// Shortest distance between (i,i) is 0
+			else
+				graph[i][j] = INF;	// Initializing other distances as infinite
+	}
+
+	for(i = 1; i <= m; i++) {
+		int u, v, w;
+		cin>> u >> v >> w;
+		graph[u][v] = w;	// input graph
+		graph[v][u] = w;	// Shortest distance between (i,j) using atmost one edge
+	}
+
+
+	for(k = 1; k <= n; k++) {
+		for(int u = 1; u <= n; u++) {
+			for(int v = 1; v <= n; v++) {
+				// Shortest distance between (i,j) using atmost k edges
+				graph[u][v] = min(graph[u][v], graph[u][k] + graph[k][v]);
+			}
+		}
+	}
+
+	// Resulting all pair shortest path in given graph
+	for(int u = 1; u <= n; u++) {
+		for(int v = 1; v <= n; v++) {
+			cout << graph[u][v] << " ";
+		}
+		cout << endl;
+	}
+	cout << endl;
+	return 0;
+}
+
+/*
+Input:-
+First line contain two space separated integer n and m
+where n is the number of vertices and m is the number
+of edges.Next m lines contains three space seprated integers
+u, v and w which represents that there is an edge between u and v
+and weight of the edge is w
+Sample Input:-
+6 9
+1 2 1
+1 3 2
+1 4 5
+2 4 5
+2 5 2
+3 4 3
+4 5 1
+4 6 1
+5 6 4
+*/

floyd_warshall_algorithm/CPP/input.txt

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+6 9
+1 2 1
+1 3 2
+1 4 5
+2 4 5
+2 5 2
+3 4 3
+4 5 1
+4 6 1
+5 6 4