new

floydWarshall.java

@@ -1 +1,82 @@
 import java.util.*;
+public class floydWarshall{
+    static void print(int u, int v, int[][]next){
+        if(next[u][v]==-1){
+            System.out.println("no path exists");
+            return;
+        }
+        System.out.print(u);
+        while(u!=v){
+            u = next[u][v];
+            System.out.print("->"+u);
+
+        } 
+        System.out.println();
+
+    }
+
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.print("\nEnter number of vertices: ");
+        int n = sc.nextInt();
+        int[][] graph = new int[n][n];
+
+        System.out.println("Enter distance matrix: ");
+        for(int i =0;i<n;i++){
+            for(int j =0;j<n;j++){
+                graph[i][j] = sc.nextInt();
+            }
+        }
+        int[][] next = new int[n][n];
+        int[][] dist = new int[n][n];
+        for(int i = 0;i<n;i++){
+            for(int j =0;j<n;j++){
+                dist[i][j] = graph[i][j];
+                if(graph[i][j]!=999 && i!=j)
+                    next[i][j] = j;
+                else
+                    next[i][j] = -1;
+            }
+        }
+        for(int k =0;k<n;k++){
+            for(int i=0;i<n;i++){
+                for(int j=0;j<n;j++){
+                    if(dist[i][k]!=999 && dist[k][j]!= 999 && dist[i][k]+dist[k][j]< dist[i][j]){
+                        dist[i][j] = dist[i][k] + dist[k][j];
+                        next[i][j] = next[i][k];
+                    }
+                }
+            }
+        }
+        boolean negativeCycle = false;
+        for(int i=0;i<n;i++){
+            if(dist[i][i]<0){
+                negativeCycle = true;
+                break;
+            }
+        }
+        if(negativeCycle){
+            System.out.println("Negative cycle exists");
+
+        }else{
+            System.out.println("No negative cycle");
+        }
+        System.out.println("Shortest path matrix");
+        for(int i=0;i<n;i++){
+            for(int j=0;j<n;j++){
+                System.out.print(dist[i][j]+ " ");
+            }
+            System.out.println();
+        }
+        System.out.print("\nEnter source vertex: ");
+        int u = sc.nextInt();
+        System.out.print("\nENter dest vertex: ");
+        int v = sc.nextInt();
+        System.out.print("\nShortes path: ");
+        print(u,v,next);
+
+        System.out.println("Cost: "+ dist[u][v]);
+        sc.close();
+
+    }
+}