HDU 3094 A tree game 树的删边游戏

叶子节点的SG值为0 非叶子节点的SG值为为它的所有子节点的SG值加1 后的异或和

#include <cstdio>#include <cstring>#include <vector>using namespace std;vector <int> G[100010];int sg[100010];int dfs(int x, int f){if(sg[x] != -1)return sg[x];if(!G[x].size())return 0;int ans = 0;for(int i = 0; i < G[x].size(); i++){int v = G[x][i];if(v == f)continue;ans ^= dfs(v, x)+1;}return ans;}int main(){int T;scanf("%d", &T);while(T--){memset(sg, -1, sizeof(sg));int n;scanf("%d", &n);for(int i = 1; i <= n; i++)G[i].clear();for(int i = 1; i < n; i++){int u, v;scanf("%d %d", &u, &v);G[u].push_back(v);G[v].push_back(u);}int ans = dfs(1, -1);if(ans)puts("Alice");elseputs("Bob");}return 0;}