JavaAlgorithms/Others/Dijkshtra.java

/**
 * @author Mayank K Jha
 */

import java.util.Arrays;
import java.util.Scanner;
import java.util.Stack;

public class Dijkshtra {

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

		// n = Number of nodes or vertices
		int n = in.nextInt();
		// m = Number of Edges
		int m = in.nextInt();

		// Adjacency Matrix
		long[][] w = new long[n + 1][n + 1];

		// 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();

			// Comparing previous edge value with current value - Cycle Case
			if (w[x][y] > cmp) {
				w[x][y] = cmp;
				w[y][x] = cmp;
			}
		}

		// Implementing Dijkshtra's Algorithm
		Stack<Integer> t = new Stack<>();
		int src = in.nextInt();

		for (int i = 1; i <= n; i++) {
			if (i != src) {
				t.push(i);
			}
		}

		Stack<Integer> p = new Stack<>();
		p.push(src);
		w[src][src] = 0;

		while (!t.isEmpty()) {
			int min = 989997979;
			int 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] + " ");
			}
			// Printing -1 if there is no path b/w given pair of edges
			else if (i != src) {
				System.out.print("-1" + " ");
			}
		}
	}
}