POJ 1949 Chores（树形dp）

#pragma warning(disable:4996)
#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
using namespace std;
const int N = 10005;

vector<int>g
;
int cnt
, cost
, n;
int ok
;

void dfs(int u) {
if (ok[u] != -1)return;
if (cnt[u] == 0) {
ok[u] = cost[u];
return;
}
int tmp = 0;
for (int i = 0; i < (int)g[u].size(); i++) {
dfs(g[u][i]);
tmp = max(tmp, ok[g[u][i]]);
}
ok[u] = tmp + cost[u];
}

int main() {
//freopen("in.txt", "r", stdin);
scanf("%d", &n);
for (int i = 1; i <= n; i++) {
int x;
scanf("%d %d", cost + i, &x);
cnt[i] = x;
while (x--) {
int v; scanf("%d", &v);
g[i].push_back(v);
}
}
int ans = 0;
memset(ok, -1, sizeof ok);
for (int i = n; i > 0; i--) {
if (ok[i] == -1)dfs(i);
ans = max(ans, ok[i]);
}
printf("%d\n", ans);
return 0;
}