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Dijkshtra's Algorithm #30

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dynamitechetan merged 4 commits into from
Apr 25, 2017
Merged

Dijkshtra's Algorithm #30

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Apr 24, 2017
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Dijkshtra's Algorithm
Apr 24, 2017
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Dijkshtra.java
Apr 24, 2017
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Dijkshtra.java
Apr 24, 2017
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56 changes: 56 additions & 0 deletions Dijkshtra.java
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/*
@author : Mayank K Jha

*/


public class Solution {

public static void main(String[] args) throws IOException {
Scanner in =new Scanner(System.in);

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){ //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++){
if(i!=src){t.push(i);}}
Stack <Integer> p=new Stack<Integer>();
p.push(src);
w[src][src]=0;
while(!t.isEmpty()){int min=989997979,loc=-1;
for(int i=0;i<t.size();i++){
w[src][t.elementAt(i)]=Math.min(w[src][t.elementAt(i)],w[src][p.peek()]
+w[p.peek()][t.elementAt(i)]);
if(w[src][t.elementAt(i)]<=min){
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"+" ");} //Printing -1 if there is no path b/w given pair of edges
}

}
}