luogu P2014 AC

// Problem: P2014 [CTSC1997] 选课
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P2014
// Memory Limit: 125 MB
// Time Limit: 1000 ms
//
// Powered by CP Editor (https://cpeditor.org)

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#define dbg(...) logger(#__VA_ARGS__, __VA_ARGS__)
template <typename... Args> void logger(string vars, Args &&... values)
{
    cerr << vars << " = ";
    string delim = "";
    (..., (cerr << delim << values, delim = ", "));
    cerr << endl;
}

template <class T> inline auto vv(int m) { return vector<vector<T>>(m, vector<T>(m)); }
template <class T> inline auto vv(int m, int n) { return vector<vector<T>>(m, vector<T>(n)); }
template <class T, T init> inline auto vv(int m) { return vector<vector<T>>(m, vector<T>(m, init)); }
template <class T, T init> inline auto vv(int m, int n) { return vector<vector<T>>(m, vector<T>(n, init)); }

template <class T> using mpq = priority_queue<T, vector<T>, greater<T>>;

using ll = long long;
using pii = pair<int, int>;
using vl = vector<ll>;
using vi = vector<int>;

vi g[512];
vi score;
int n, m;
vector<vector<int>> dp;

int dfs(int u)
{
    int cnt = 1;
    dp[u][0] = 0;
    dp[u][1] = score[u];
    for (auto v : g[u]) {
        auto subcnt = dfs(v);
        cnt += subcnt;
        for (int j = cnt; j > 0; --j)
            for (int k = 1; k <= subcnt; ++k)
                if (j - k > 0)
                    dp[u][j] = max(dp[u][j], dp[u][j - k] + dp[v][k]);
    }
    return cnt;
}

int main(int argc, char **argv)
{
    cin >> n >> m;
    score = vi(n + 1);
    for (int i = 1; i <= n; ++i) {
        int k;
        cin >> k >> score[i];
        g[k].push_back(i);
    }
    dp = vv<int, INT_MIN / 2>(n + 1, n + 1);
    dfs(0);
    cout << dp[0][m + 1] << endl;
    return 0;
};