：求问这个地方的欧拉降幂a^b%p  为甚麽默认b小于等于m[p]..直接采用a^(b%m[p]) %p 而不是  a^(b%m[p]+m[p])%p??? 即quick_pow(2,dfs(i-1,m[mod])+1,mod)为甚麽不是quick_pow(2,dfs(i-1,m[mod])+1+m[mod],mod)??

你以为你CF过了四题：也可以把边集状压存下来，用set判重就好。 #include <bits/stdc++.h> using namespace std; const int N = 10; int G[N][N]; vector<pair<int, int>> edges; map<pair<int, int>, int> dic; int getid(int x, int y) { if (x > y) swap(x, y); assert(x < y); if (dic[{x, y}]) return dic[{x, y}]; return dic[{x, y}] = dic.size(); } long long check() { long long hash = 0; for (auto& e : edges) { int u = p[e.first], v = p[e.second]; if (G[u][v]) hash |= 1LL << getid(u, v); else return -1; } return hash; } int main() { int n, a, b; while (~scanf("%d%d%d", &n, &a, &b)) { memset(G, 0, sizeof(G)); dic.clear(); edges.clear(); for (int i = 0, u, v; i < a; i++) { scanf("%d%d", &u, &v); --u, --v; edges.emplace_back(u, v); } for (int i = 0, u, v; i < b; i++) { scanf("%d%d", &u, &v); --u, --v; G[u][v] = G[v][u] = 1; getid(u, v); } for (int i = 0; i < n; i++) p[i] = i; set<long long> s; do { int tmp = check(); if (~tmp) s.insert(tmp); } while (next_permutation(p, p + n)); int ans = s.size(); printf("%d\n", ans); } }