java-用邻接矩阵求图的最短路径、最长路径。弗洛伊德算法

see  
http://eriol.iteye.com/blog/1186408
http://blog.csdn.net/vinglemar/article/details/3605813

import java.util.ArrayList;
import java.util.List;


public class FloydInGraph {

	/**
	 * 图	邻接矩阵 		最短路径		弗洛伊德算法
	 */
	private static int INF=Integer.MAX_VALUE;
         //dist[i][j]=INF<==>no edges between i and j
	private int[][] dist;
         //the distance between i and j.At first,dist[i][j] is the weight of edge [i,j]  
	private int[][] path;  
	private List<Integer> result=new ArrayList<Integer>();
	
	public static void main(String[] args) {
		FloydInGraph graph=new FloydInGraph(5);
		int[][] matrix={
				{INF,30,INF,10,50},
				{INF,INF,60,INF,INF},
				{INF,INF,INF,INF,INF},
				{INF,INF,INF,INF,30},
				{50,INF,40,INF,INF},
		};
		int begin=0;
		int end=4;
		graph.findCheapestPath(begin,end,matrix);
		List<Integer> list=graph.result;
		System.out.println(begin+" to "+end+",the cheapest path is:");
		System.out.println(list.toString());
		System.out.println(graph.dist[begin][end]);
	}

	public  void findCheapestPath(int begin,int end,int[][] matrix){
		floyd(matrix);
		result.add(begin);
		findPath(begin,end);
		result.add(end);
	}
	
	public void findPath(int i,int j){
		int k=path[i][j];
		if(k==-1)return;
		findPath(i,k);
		result.add(k);
		findPath(k,j);
	}
	public  void floyd(int[][] matrix){
		int size=matrix.length;
		//initialize dist and path
		for(int i=0;i<size;i++){
			for(int j=0;j<size;j++){
				path[i][j]=-1;
				dist[i][j]=matrix[i][j];
			}
		}
		for(int k=0;k<size;k++){
			for(int i=0;i<size;i++){
				for(int j=0;j<size;j++){
					if(dist[i][k]!=INF&&
						dist[k][j]!=INF&&
						dist[i][k]+dist[k][j]<dist[i][j]){//dist[i][k]+dist[k][j]>dist[i][j]-->longestPath
						dist[i][j]=dist[i][k]+dist[k][j];
						path[i][j]=k;
					}
				}
			}
		}
		
	}
	
	public FloydInGraph(int size){
		this.path=new int[size][size];
		this.dist=new int[size][size];
	}
}