f[i][0]表示不选当前节点,当前节点的所有儿子节点都选
f[i][1]表示选当前节点,儿子节点可选可不选
#include <cstdio> #include <cstring> #include <iostream> #define N 1501 #define min(x, y) ((x) < (y) ? (x) : (y)) int n, cnt; int head[N], to[N << 1], next[N << 1], f[N][2]; bool vis[N]; //f[i][0]表示不选当前节点,当前节点的所有儿子节点都选 //f[i][1]表示选当前节点,儿子节点可选可不选 inline int read() { int x = 0, f = 1; char ch = getchar(); for(; !isdigit(ch); ch = getchar()) if(ch == ‘-‘) f = -1; for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - ‘0‘; return x * f; } inline void add(int x, int y) { to[cnt] = y; next[cnt] = head[x]; head[x] = cnt++; } inline void dfs(int u) { int i, v; f[u][1] = vis[u] = 1; for(i = head[u]; i ^ -1; i = next[i]) { v = to[i]; if(!vis[v]) { dfs(v); f[u][0] += f[v][1]; f[u][1] += min(f[v][0], f[v][1]); } } } int main() { int i, j, k, x, y; n = read(); memset(head, -1, sizeof(head)); for(i = 1; i <= n; i++) { x = read() + 1; k = read(); for(j = 1; j <= k; j++) { y = read() + 1; add(x, y); add(y, x); } } dfs(1); printf("%d\n", min(f[1][0], f[1][1])); return 0; }
时间: 2024-10-10 18:23:13