Submission #1201428

#	Time	Username	Problem	Language	Result	Execution time	Memory
1201428		CrabCNH	Biochips (IZhO12_biochips)	C++20	100 / 100	460 ms	407392 KiB

biochips

#include <bits/stdc++.h>

#define task   "BriantheCrab"

#define pii    pair <int, int>
#define fi     first
#define se     second
#define szf    sizeof
#define sz(s)  (int)((s).size())

using namespace std;

template <class T> void mini (T &t, T f) {if (t > f) t = f;}
template <class T> void maxi (T &t, T f) {if (t < f) t = f;}

const int maxN = 2e5 + 5;
const int maxM = 5e2 + 5;
const int inf = 1e3 + 7;
const int mod = 1e9 + 7;

int n, m, rt;
int c[maxN], sz[maxN];
vector <int> adj[maxN];
int dp[maxN][maxM];

void dfs (int u, int p) {
    sz[u] = 1;
    dp[u][0] = 0;
    for (auto v : adj[u]) {
        if (v == p) {
            continue;
        }
        dfs (v, u);
        for (int j = min (sz[u], m); j >= 0; j --) {
            for (int k = min (sz[v], m - j); k >= 0; k --) {
                maxi (dp[u][j + k], dp[u][j] + dp[v][k]);
            }
        }
        sz[u] += sz[v];
    }
    maxi (dp[u][1], c[u]);
    // for (int i = 0; i <= sz[u]; i ++) {
        // cout << u << ' ' << dp[u][i] << '\n';
    // }
}

void solve () {
    cin >> n >> m;
    for (int i = 1; i <= n; i ++) {
        int p;
        cin >> p >> c[i];
        if (p != 0) {
            adj[p].push_back (i);
            adj[i].push_back (p);
            //cout << i << ' ' << p << '\n';
        }
        else {
            rt = i;
        }
    }
    for (int i = 1; i <= n; i ++) {
        for (int j = 0; j <= m; j ++) {
            dp[i][j] = -inf;
        }
    }
    dfs (rt, rt);
    cout << dp[rt][m];
}

signed main () {
    cin.tie (nullptr) -> sync_with_stdio (false);
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    int t = 1;
    //cin >> t;
    while (t --) {
        solve ();
    } 
    return 0;
}
// thfdgb

Compilation message (stderr)

biochips.cpp: In function 'int main()':
biochips.cpp:73:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
biochips.cpp:74:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100