dijkstra

// A Java program for Dijkstra's single source shortest path algorithm.
// The program is for adjacency matrix representation of the graph
import java.util.*;
import java.util.Scanner;
import java.lang.*;
import java.io.*;

public class ShortestPath {
	// A utility function to find the vertex with minimum distance value,
	// from the set of vertices not yet included in shortest path tree
	static int SV = 0;
	static int N = 0;
	static int dist[];

	public static int minDistance(int dist[], Boolean sptSet[]) {
		// Initialize min value
		int min = Integer.MAX_VALUE, min_index = -1;
		for (int v = 0; v < N; v++)
			if (sptSet[v] == false && dist[v] <= min) {
				min = dist[v];
				min_index = v;
			}

		return min_index;
	}

	 // A utility function to print the constructed distance array
	public static void printSolution(int dist[], int n) {
		for (int i = 0; i < N; i++)
		System.out.println("[" + dist[i] + "]");



}

	// Funtion that implements Dijkstra's single source shortest path
	public void dijkstra(int graph[][], int src) {
		int dist[] = new int[N]; // The output array. dist[i] will hold
									// the shortest distance from src to i

		// sptSet[i] will true if vertex i is included in shortest
		// path tree or shortest distance from src to i is finalized
		Boolean sptSet[] = new Boolean[N];

		// Initialize all distances as INFINITE and stpSet[] as false
		for (int i = 0; i < N; i++) {
			dist[i] = Integer.MAX_VALUE;
			sptSet[i] = false;
		}

		// Distance of source vertex from itself is always 0
		dist[src] = 0;

		// Find shortest path for all vertices
		for (int count = 0; count < N - 1; count++) {
			// Pick the minimum distance vertex from the set of vertices
			// not yet processed. u is always equal to src in first
			// iteration.
			int u = minDistance(dist, sptSet);

			// Mark the picked vertex as processed
			sptSet[u] = true;

			// Update dist value of the adjacent vertices of the
			// picked vertex.
			for (int v = 0; v < N; v++)

				// Update dist[v] only if is not in sptSet, there is an
				// edge from u to v, and total weight of path from src to
				// v through u is smaller than current value of dist[v]
				if (!sptSet[v] && graph[u][v] != 0 && dist[u] != Integer.MAX_VALUE && dist[u] + graph[u][v] < dist[v])
					dist[v] = dist[u] + graph[u][v];


		}

		// print the constructed distance array
		printSolution(dist, N);


	}



	public static void printMatrix(int[][] Matrix) {
		for (int i = 0; i < N; i++) {
			for (int j = 0; j < N; j++) {
				System.out.print(Matrix[i][j]);
				System.out.print(" ");

			}
			System.out.println();
		}}


	// Driver method
	public static void main(String[] args) throws FileNotFoundException {
		int[][] M = null;
		try {
			int i = 0, j = 0; // counters
			FileInputStream textFile = new FileInputStream("EXAMPLE(2).txt"); // name of input file must go in here
			Scanner scan = new Scanner(textFile);
			N = scan.nextInt(); // read in the size
			String flush = scan.nextLine(); // gets rid of linefeed
			M = new int[N][N]; // instantiates array
			// this loop reads in matrix from input file
			String line;
			while (i < N && (line = scan.nextLine()) != null) {
				j = 0;
				String delim = " ";
				String tokens[] = line.split(delim);
				for (String a : tokens) {
					M[i][j] = Integer.parseInt(a);
					j++;
				}
				i++;
			}
			if (i > N);
			SV = scan.nextInt();
		} catch (Exception e) {
			e.printStackTrace();
		}
		//PrintSolution(dist);
		ShortestPath t = new ShortestPath();
		System.out.println(N);
		printMatrix(M);
		System.out.println(SV);
		System.out.println("\t\t");
		 t.dijkstra(M, SV - 1);


		try {
			FileWriter fw = new FileWriter("dijkstra.txt"); // writes transitive closure to file
					for (int i = 0; i < N; i++)
						fw.write(t.dijkstra(M, SV - 1));

				System.out.println("\n");
				fw.write(" \n");

			// fw.write("time in milliseconds" + Ttime / 1000000); // writes runtime to file
			System.out.println("\n");
			fw.close();
		} catch (Exception e) {
			System.out.println(e);
		}




	}
}