Dijkshtra's Algorithm

Mayank Kumar Jha · web-flow · commit 9d2374ffbeb4 · 2017-04-24T19:24:24.000+05:30
diff --git a/Dijkshtra.java b/Dijkshtra.java
@@ -1,20 +1,28 @@
 public static void main(String[] args) throws IOException {
 	  Reader in=new Reader();
 	  int t1=in.nextInt();
-        for(int gj=0;gj<t1;gj++)
-	{
-        int n=in.nextInt();
-        int m=in.nextInt();
-        long w[][]=new long [n+1][n+1];
-        for (long[] row: w)
+      
+	int n=in.nextInt();             //n = Number of nodes or vertices
+        int m=in.nextInt();             //m = Number of Edges
+        long w[][]=new long [n+1][n+1]; //Adjacency Matrix  
+        
+	//Initializing Matrix with Certain Maximum Value for path b/w any two vertices 
+	for (long[] row: w)
             Arrays.fill(row, 1000000l);
+	//From above,we Have assumed that,initially path b/w any two Pair of vertices is Infinite such that Infinite = 1000000l
+	//For simplicity , We can also take path Value = Long.MAX_VALUE , but i have taken Max Value = 1000000l .
+	
+	//Taking Input as Edge Location b/w a pair of vertices
          for(int i=0;i<m;i++){
              int x=in.nextInt(),y=in.nextInt();
              long cmp=in.nextLong();
-             if(w[x][y]>cmp){
-            	w[x][y]=cmp; w[y][x]=cmp;
+             if(w[x][y]>cmp){                      //Comparing previous edge value with current value  -  Cycle Case
+            	w[x][y]=cmp; w[y][x]=cmp;        
              }
 	}
+	
+	//Implementing Dijkshtra's Algorithm 
+	
          Stack <Integer> t=new Stack<Integer>();
           int src=in.nextInt();
         for(int i=1;i<=n;i++){
@@ -30,9 +38,11 @@ public static void main(String[] args) throws IOException {
             	min=(int) w[src][t.elementAt(i)];loc=i;}
         }
         p.push(t.elementAt(loc));t.removeElementAt(loc);}
+	
+	//Printing shortest path from the given source src
          for(int i=1;i<=n;i++){
         	 if(i!=src && w[src][i]!=1000000l){System.out.print(w[src][i]+" ");}
-        	 else if(i!=src){System.out.print("-1"+" ");}
-         }System.out.println();
+        	 else if(i!=src){System.out.print("-1"+" ");}    //Printing -1 if there is no path b/w given pair of edges
          }
+         
   }
