有向图 获取回路转

import java.util.ArrayList;

public class TESTHUAN {

static private int[] visited = { 0, 0, 0, 0, 0, 0, 0 };// 7个节点,0为未访问

static private int[][] e = { 

{ 0, 1, 1, 0, 0, 0, 0 }, 

{ 0, 0, 1, 1, 0, 0, 0 }, 

{ 1, 0, 0, 0, 0, 1, 0 }, 

{ 0, 0, 0, 0, 1, 0, 0 }, 

{ 0, 0, 0, 0, 0, 0, 0 }, 

{ 0, 0, 0, 0, 0, 0, 1 }, 

{ 1, 0, 0, 0, 0, 0, 0 } 

};// 邻接矩阵,值大家任意改.

static ArrayList trace = new ArrayList();// 从出发节点到当前节点的轨迹

static boolean hasCycle = false;

public static void main(String[] args) {

findCycle(0);

if (!hasCycle)

System.out.println("No Cycle.");

}

static void findCycle(int v) // 递归DFS

{

if (visited[v] == 1) {

int j;

if ((j = trace.indexOf(v)) != -1) {

hasCycle = true;

System.out.print("Cycle:");

while (j < trace.size()) {

System.out.print(trace.get(j) + " ");

j++;

}

System.out.print("\n");

return;

}

return;

}

visited[v] = 1;

trace.add(v);

for (int i = 0; i < 7; i++) {

if (e[v][i] == 1)

findCycle(i);

}

trace.remove(trace.size() - 1);

}

}