# 第一题:大意是给一棵树,输出有几个节点满足恰好有两个子节点 #include <bits/stdc++.h> using namespace std; const int N = 110, M = 110; int n, m; int h[N], e[M], ne[M], idx; int son_cnt[N]; bool is_leaf[N]; bool din[N]; int root, res; void add(int a, int b) { e[idx] = b, ne[idx] = h[a], h[a] = idx ++ ; } void dfs...