HDU-1561

依赖背包转化为树形dp

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#include <vector>
#define max(x, y) (x > y ? x : y)
#define min(x, y) (x > y ? y : x)
#define INF 0x3f3f3f3f
#define MOD 1000000007
#define Yes printf("Yes
")
#define No printf("No
")
using namespace std;
typedef long long LL;
typedef pair<int, int> PII;

const int maxn = 210;
int dp[maxn][maxn];

vector<int> G[maxn];
int N, M;

void dfs(int node, int m) {
    for (int i = 0; i < G[node].size(); i++) {
        if (m > 1) dfs(G[node][i], m - 1);
        for (int j = m + 1; j >= 2; j--) {
            for (int k = 1; k < j; k++) {
                dp[node][j] = max(dp[node][j], dp[node][j - k] + dp[G[node][i]][k]);
            }
        }
    }
}

int main(int argc, const char * argv[]) {
    while (scanf("%d%d", &N, &M), N + M) {
        int u;
        memset(dp, 0, sizeof(dp));
        for (int i = 0; i <= N; i++) G[i].clear();
        for (int i = 1; i <= N; i++) {
            scanf("%d%d", &u, &dp[i][1]);
            G[u].push_back(i);
        }
        dfs(0, M);
        printf("%d
", dp[0][M + 1]);
    }
    return 0;
}