利用并查集建好图后：不断地求最大匹配、删除匹配边直到最大匹配不够n。
1 #include <algorithm> 2 #include <iostream> 3 #include <cstring> 4 #include <cstdio> 5 using namespace std; 6 7 const int N = 101; 8 bool mp[N][N]; 9 int mark[N]; 10 bool visit[N]; 11 int fa[N]; 12 int n, m, f; 13 14 struct Edge 15 { 16 int from, to; 17 } edge[N * N]; 18 19 int findf( int x ) 20 { 21 if ( fa[x] != x ) fa[x] = findf(fa[x]); 22 return fa[x]; 23 } 24 25 void union_set( int x, int y ) 26 { 27 x = findf(x), y = findf(y); 28 if ( x != y ) 29 { 30 fa[x] = y; 31 } 32 } 33 34 int dfs( int u ) 35 { 36 for ( int i = 1; i <= n; i++ ) 37 { 38 if ( !visit[i] && mp[u][i] ) 39 { 40 visit[i] = 1; 41 if ( mark[i] == -1 || dfs(mark[i]) ) 42 { 43 mark[i] = u; 44 return 1; 45 } 46 } 47 } 48 return 0; 49 } 50 51 int hunagry() 52 { 53 int res = 0; 54 memset( mark, -1, sizeof(mark) ); 55 for ( int i = 1; i <= n; i++ ) 56 { 57 memset( visit, 0, sizeof(visit) ); 58 res += dfs(i); 59 } 60 return res; 61 } 62 63 void deleteEdge() 64 { 65 for ( int i = 1; i <= n; i++ ) 66 { 67 mp[mark[i]][i] = 0; 68 } 69 } 70 71 int main () 72 { 73 int t; 74 scanf("%d", &t); 75 while ( t-- ) 76 { 77 scanf("%d%d%d", &n, &m, &f); 78 for ( int i = 1; i <= m; i++ ) scanf("%d%d", &edge[i].from, &edge[i].to); 79 memset( mp, 0, sizeof(mp) ); 80 for ( int i = 1; i <= n; i++ ) fa[i] = i; 81 for ( int i = 1; i <= f; i++ ) 82 { 83 int p, q; 84 scanf("%d%d", &p, &q); 85 union_set( p, q ); 86 } 87 for ( int i = 1; i <= m; i++ ) 88 { 89 mp[findf(edge[i].from)][edge[i].to] = 1; 90 } 91 for ( int i = 1; i <= n; i++ ) 92 { 93 int o = findf(i); 94 if ( o == i ) continue; 95 for ( int j = 1; j <= n; j++ ) 96 { 97 mp[i][j] = mp[o][j]; 98 } 99 } 100 int ans = 0; 101 while ( hunagry() == n ) 102 { 103 ans++; 104 deleteEdge(); 105 } 106 printf("%d ", ans); 107 } 108 return 0; 109 }