dijkstra算法JAVA实现

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import java.util.ArrayList;import java.util.HashMap;import java.util.Map;/** * Created by Smeiling on 2017/3/26. */public class MyDijkstra2 {    private static final int INT_MIN = 0;    private static final int INT_MAX = Integer.MAX_VALUE;    private Map<Integer, Integer> distance = new HashMap<Integer, Integer>();    private Map<Integer, Integer> prevVertex = new HashMap<Integer, Integer>();    void Dijkstra(int numOfVertex, int startVertex, int[][] map)    {        Map<Integer, Boolean> isInS = new HashMap<Integer, Boolean>();        for (int k = 0; k < numOfVertex; k++)            isInS.put(k, false);        for (int i = 0; i < numOfVertex; ++i) {            distance.put(i, map[startVertex][i]);            if (map[startVertex][i] < INT_MAX)                prevVertex.put(i, startVertex);            else                prevVertex.put(i, -1);        }        prevVertex.put(startVertex, -1);/* 开始使用贪心思想循环处理不在S集合中的每一个节点 */        isInS.put(startVertex, true);        int u = startVertex;        for (int i = 1; i < numOfVertex; i++) // 这里循环从1开始是因为开始节点已经存放在S中了，还有numOfVertex-1个节点要处理        {            int nextVertex = u;            int tempDistance = INT_MAX;            for (int j = 0; j < numOfVertex; ++j) {                if ((isInS.get(j) == false) && (distance.get(j) < tempDistance))// 寻找不在S集合中的distance最小的节点                {                    nextVertex = j;                    tempDistance = distance.get(j);                }            }            isInS.put(nextVertex, true);            u = nextVertex;// 下一次寻找的开始节点            for (int j = 0; j < numOfVertex; j++) {                if (isInS.get(j) == false && map[u][j] < INT_MAX) {                    int temp = distance.get(u) + map[u][j];                    if (temp < distance.get(j)) {                        distance.put(j, temp);// distance[ j ] = temp;                        prevVertex.put(j, u);// prevVertex[ j ] = u;                    }                }            }        }    }    void print()    {        for (int j = 0; j < 5; ++j)        {            int index = j;            ArrayList<Integer> trace = new ArrayList<Integer>();            while (prevVertex.get(index) != -1)            {                trace.add(prevVertex.get(index));                index = prevVertex.get(index);// preVertex[index];            }            System.out.print("路径：");// cout << "路径：";            for (int q = trace.size()-1; q >=0; q--) {            // includeIDs+=pass.get(entry.getKey()).get(i)+",";                System.out.print(trace.get(q) + "->");            }            System.out.print(j);            System.out.println("距离是：" + distance.get(j));        }    }    public static void main(String[] args) {        int map[][] = { // 定义有向图也可以是无向图（对称矩阵）                { INT_MIN, 10, 5, INT_MAX, 20 },                { 10, INT_MIN, 2, 17, INT_MAX},                { 5, 2, INT_MIN, INT_MAX, INT_MAX },                { INT_MAX, 17, INT_MAX, INT_MIN, 8 },                { 20, INT_MAX, INT_MAX, 8, INT_MIN } };        for (int i = 0; i < 5; ++i) {            MyDijkstra2 dj = new MyDijkstra2();            dj.Dijkstra(5, i, map);            dj.print();        }    }}
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