不熟悉的点：
1.并查集的按秩压缩
2.vector建图
3.bfs拓扑排序
1 #include "cstdio" 2 #include "iostream" 3 #include "cstring" 4 #include "vector" 5 #include "queue" 6 using namespace std; 7 const int N = 10005; 8 int n, m, t; 9 int fa[N]; 10 int X[2 * N], Y[2 * N]; 11 int son[N]; 12 char O[2 * N]; 13 vector<int>G[N]; 14 15 void init(int n) 16 { 17 for (int i = 0; i <= n; ++i) 18 fa[i] = -1; 19 for (int i = 0; i <= n; ++i) 20 G[i].clear(); 21 memset(son, 0, sizeof(son)); 22 } 23 int find(int x) 24 { 25 if (fa[x] < 0) return x; 26 return fa[x] = find(fa[x]); 27 } 28 29 bool merg(int a, int b) 30 { 31 int x = find(a); 32 int y = find(b); 33 if (x == y) return false; 34 else if (x < y){ 35 fa[x] += fa[y]; 36 fa[y] = x; 37 } 38 else { 39 fa[y] += fa[x]; 40 fa[x] = y; 41 } 42 return true; 43 } 44 45 int main() 46 { 47 while (cin >> n >> m) { 48 init(n); 49 int num = n; 50 for (int i = 0; i < m; ++i) { 51 cin >> X[i] >> O[i] >> Y[i]; 52 if (O[i] == '=') { 53 if (merg(X[i], Y[i])) 54 num--; 55 } 56 } 57 for (int i = 0; i < m; ++i) if (O[i] != '=') { 58 int x = find(X[i]); 59 int y = find(Y[i]); 60 if (O[i] == '>') { 61 G[x].push_back(y); 62 son[y]++; 63 } 64 else { 65 G[y].push_back(x); 66 son[x]++; 67 } 68 } 69 queue<int> q; 70 for (int i = 0; i < n; ++i) 71 if (son[i] == 0 && i == find(i)) 72 q.push(i); 73 int sin = 0; 74 while (!q.empty()) { 75 if (q.size() > 1) sin = 1; 76 int t = q.front(); 77 q.pop(); 78 --num; 79 for (int v = 0; v < G[t].size(); ++v) { 80 if (--son[G[t][v]] == 0) 81 q.push(G[t][v]); 82 } 83 } 84 if (num > 0) cout << "CONFLICT" << endl; 85 else if (sin) cout << "UNCERTAIN" << endl; 86 else cout << "OK" << endl; 87 } 88 return 0; 89 }