Legal or Not HDU

注意点：输入数据中可能有重复，需要进行处理！
 1 #include <stdio.h>
 2 #include <iostream>
 3 #include <cstring>
 4 #include <vector>
 5 #include <algorithm>
 6 #include <sstream>
 7 
 8 
 9 using namespace std;
10 
11 int n, m;
12 
13 int indegree[101];
14 int g[101][101]; 
15 
16 int main()
17 {
18     while(scanf("%d %d", &n, &m) != EOF)
19     {
20         if(n == 0 && m == 0)
21             break;
22         
23         memset(indegree, 0, sizeof(indegree));
24         memset(g, 0, sizeof(g));
25         
26         int a, b;
27         for(int i = 1; i <= m; ++i)
28         {
29             scanf("%d %d", &a, &b);
30             
31             if(g[a][b] == 0)    // 输入中有可能有反复输入如1,2；1,2这种情况！！！ 
32             {
33                 g[a][b] = 1;
34                 indegree[b]++;
35             }
36             
37         }
38         
39         int cnt = 0;
40         
41         for(int k = 0; k < n; ++k)
42         {
43             int i, j; 
44             for(i = 0; i < n; ++i)
45             {
46                 if(indegree[i] == 0)
47                 {
48                     indegree[i] = -1;
49                     cnt++;
50                     break;
51                 }
52             } 
53             
54             for(j = 0; j < n; ++j)
55             {
56                 if(g[i][j] == 1)
57                 {
58                     indegree[j]--;
59                     g[i][j] == 0;
60                 }
61             }
62         }
63         
64         
65         if(cnt == n)
66             cout << "YES" << endl;
67         else
68             cout << "NO" << endl;
69     }
70        
71     return 0;
72 }