package com.liuzhen.practice;import java.util.ArrayList;
import java.util.Scanner;public class Main {public static int maxV = Integer.MAX_VALUE;public static int[][] capacity = new int[6][6]; //用于统计给定图前向边和后向边剩余流量public static int[] flow = new int[6];  //用于统计从源点到图中任意一点i的最大可增加的流量public static int[] pre = new int[6];  //用于记录当前到达顶点的前驱顶点public int bfs(int[][] graph) {  //使用BFS遍历，寻找给定图的增广路径ArrayList<Integer> list = new ArrayList<Integer>();list.add(0);      //源点为顶点0for(int i = 0;i < 6;i++) {pre[i] = -1;   //初始化所有顶点的前驱顶点为-1
        }pre[0] = 0;     //源点的前驱顶点设定为自己flow[0] = maxV; //源点的前驱顶点到源点的增加流量设定为无穷大while(!list.isEmpty()) {int index = list.get(0);list.remove(0);if(index == 5)break;for(int i = 0;i < graph.length;i++) {if(capacity[index][i] > 0 && pre[i] == -1) {//当顶点i未被访问且到达顶点i有剩余流量时pre[i] = index;  //顶点i的前驱顶点为indexflow[i] = Math.min(flow[index], capacity[index][i]);list.add(i);}}}if(pre[5] != -1)return flow[5];return -1;}public void getResult(int[][] graph) {int result = 0;int temp = bfs(graph);while(temp != -1) {result = result + temp;int start = pre[5];int end = 5;while(start != 0) {capacity[start][end] -= temp;   //前向边剩余流量减少tempcapacity[end][start] += temp;   //后向边剩余流量增加tempend = start;start = pre[end];}capacity[0][end] -= temp;capacity[end][0] += temp;temp = bfs(graph);}System.out.println("给定图的最大流量为："+result);return;}public static void main(String[] args) {Main test = new Main();int[][] graph = new int[6][6];Scanner in = new Scanner(System.in);int num = in.nextInt();   // 给定图的边数目for(int i = 0;i < num;i++) {int a = in.nextInt();int b = in.nextInt();int value = in.nextInt();graph[a - 1][b - 1] = value;capacity[a - 1][b - 1] = value;//前向边起始剩余流量为边的容量，后向边起始剩余流量为0
        }test.getResult(graph);}
}

7
1 2 2
1 3 4
2 5 3
2 3 5
4 3 1
5 6 4
3 2 6
给定图的最大流量为：3