java实现-图的相关操作

import java.util.LinkedList;

public class Graph {
    private int vertexSize;//顶点的数量
    private int[] vertexs;//顶点数组
    private int[][] matrix;//矩阵
    private boolean[] isVisited;//是否访问过
    private static final int MAX_WEIGHT = 1000;

    public Graph(int vertexSize){
        this.vertexSize = vertexSize;
        matrix = new int[vertexSize][vertexSize];
        vertexs = new int[vertexSize];
        for(int i = 0;i < vertexSize;i++){
            vertexs[i] = i;
        }
        isVisited = new boolean[vertexSize];
    }

    public int getVertexSize() {
        return vertexSize;
    }

    public void setVertexSize(int vertexSize) {
        this.vertexSize = vertexSize;
    }

    public int[] getVertexs() {
        return vertexs;
    }

    public void setVertexs(int[] vertexs) {
        this.vertexs = vertexs;
    }

    public int[][] getMatrix() {
        return matrix;
    }

    public void setMatrix(int[][] matrix) {
        this.matrix = matrix;
    }

    //获取某个顶点的出度
    public int getOutDegree(int index){
        int[] arr = matrix[index];
        int degree = 0;
        for(int i = 0;i < arr.length;i++){
            if(arr[i] !=0 && arr[i] < MAX_WEIGHT){
                degree++;
            }
        }
        return degree;
    }

    //获取两个顶点之间的权值
    public int getWeight(int v1,int v2){
        return matrix[v1][v2] == 0 ? 0 : (matrix[v1][v2] == MAX_WEIGHT ? -1 : matrix[v1][v2]);
    }

    //深度优先遍历
    private void depthFirstSearch(int i){
        isVisited[i] = true;
        int w = getFirstNeighor(i);
        while(w != -1){
            if (!isVisited[w]){//需要遍历该顶点
                System.out.println("访问到了 " + w + "顶点");
                depthFirstSearch(w);
            }
            w = getNextNeighor(i,w);//第一个相对于w的邻接点

        }
    }

    //对外提供深度优先遍历
    public void depthFirstSearch(){
        isVisited = new boolean[vertexSize];
        for(int i = 0;i < vertexSize;i++){
            if(!isVisited[i]){
                System.out.println("访问到了 " + i + "顶点");
                depthFirstSearch(i);
            }
        }
        isVisited = new boolean[vertexSize];
    }

    //广度优先遍历(使用到了队列)
    public void broadFirstSearch(){
        isVisited = new boolean[vertexSize];
        for(int i = 0;i < vertexSize;i++){
            if(!isVisited[i]){
                broadFirstSearch(i);
            }
        }
        isVisited = new boolean[vertexSize];
    }

    private void broadFirstSearch(int i){
        int u;//获取队列的头结点
        int w;//获取第一个邻接点
        LinkedList<Integer> queue = new LinkedList<>();
        System.out.println("访问到了 " + i + "结点");
        isVisited[i] = true;
        queue.add(i);
        while(!queue.isEmpty()){
            u = (Integer)(queue.removeFirst()).intValue();
            w = getFirstNeighor(u);
            while(w != -1){
                if(!isVisited[w]) {
                    System.out.println("访问到了 " + w + "结点");
                    isVisited[w] = true;
                    queue.add(w);
                }
                w = getNextNeighor(u,w);
            }

        }
    }

    //获取某个结点的第一个邻接点
    public int getFirstNeighor(int index){
        for(int i = 0;i < vertexSize;i++){
            if(matrix[index][i] > 0 && matrix[index][i] < MAX_WEIGHT){
                return i;
            }
        }
        return -1;
    }

    //根据前一个邻接点的下标来获取下一个邻接点(就是根据相对于第一个邻接点获取下一个邻接点)
    /*
    *  @param v1表示要找的顶点
    *  @param v2表示该顶点相对于哪个邻接点去获取下一个邻接点
    * **/
    public int getNextNeighor(int v1,int v2){
        for(int i = v2 + 1;i < vertexSize;i++){
            if(matrix[v1][i] > 0 && matrix[v1][i] < MAX_WEIGHT){
                return i;
            }
        }
        return -1;
    }


    //普里母算法
    public void prim(){
        int[] lowcost = new int[vertexSize];    //最小代价顶点权值的数组，为0表示已经获取到了最小的权值
        int[] adjvex = new int[vertexSize];     //放顶点权值
        int min = 0;//最小值
        int minId = 0;//最小的下标
        int sum = 0;    //总和
        for(int i = 1;i < vertexSize;i++){
            lowcost[i] = matrix[0][i];
        }

        for(int i = 1;i < vertexSize;i++){
            min = MAX_WEIGHT;
            minId = 0;
            for(int j = 1;j < vertexSize;j++){
                if(lowcost[j] < min && lowcost[j] > 0){
                    min = lowcost[j];
                    minId = j;
                }
            }
//            for(int a = 0;a < vertexSize;a++){
//                System.out.print(adjvex[a] + " ");
//            }
            System.out.println("顶点为:" + adjvex[minId] + "，权值为:" + min + "最小值的下标为:" + minId);

            sum += min;
            lowcost[minId] = 0;
            for(int j = 1;j < vertexSize;j++){
                if(lowcost[j] != 0 && matrix[minId][j] < lowcost[j]){
                    lowcost[j] = matrix[minId][j];
                    adjvex[j] = minId;
                }
            }
        }
        System.out.println("最小生成树的权值和为:" + sum);

    }



    public static void main(String[] args){
        Graph graph = new Graph(9);
        int[] a1 = new int[]{0,10,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,11,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT};
        int[] a2 = new int[]{10,0,18,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,16,MAX_WEIGHT,12};
        int[] a3 = new int[]{MAX_WEIGHT,MAX_WEIGHT,0,22,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,8};
        int[] a4 = new int[]{MAX_WEIGHT,MAX_WEIGHT,22,0,20,MAX_WEIGHT,24,16,21};
        int[] a5 = new int[]{MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,20,0,26,MAX_WEIGHT,7,MAX_WEIGHT};
        int[] a6 = new int[]{11,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,26,0,17,MAX_WEIGHT,MAX_WEIGHT};
        int[] a7 = new int[]{MAX_WEIGHT,16,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,17,0,19,MAX_WEIGHT};
        int[] a8 = new int[]{MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,16,7,MAX_WEIGHT,19,0,MAX_WEIGHT};
        int[] a9 = new int[]{MAX_WEIGHT,12,8,21,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,MAX_WEIGHT,0};
        graph.matrix[0] = a1;
        graph.matrix[1] = a2;
        graph.matrix[2] = a3;
        graph.matrix[3] = a4;
        graph.matrix[4] = a5;
        graph.matrix[5] = a6;
        graph.matrix[6] = a7;
        graph.matrix[7] = a8;
        graph.matrix[8] = a9;

//        System.out.println("出度为:" + graph.getOutDegree(4));
//        System.out.println("权值:" + graph.getWeight(0,4));
    }
}