Submission #1069342

#	Time	Username	Problem	Language	Result	Execution time	Memory
1069342		VMaksimoski008	Biochips (IZhO12_biochips)	C++17	90 / 100	456 ms	405084 KiB

biochips

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const int maxn = 2e5 + 5;

int n, m, root, par[maxn], val[maxn], in[maxn], out[maxn], dp[maxn][505], timer = 0;
vector<int> graph[maxn], euler;

void dfs(int u) {
    in[u] = timer++; euler.push_back(u);
    for(int &v : graph[u]) dfs(v);
    out[u] = timer - 1;
}

inline bool anc(int u, int v) {
    return in[u] <= in[v] && out[v] <= out[u];
}

int main() {
    cin >> n >> m;
    for(int i=1; i<=n; i++) {
        cin >> par[i] >> val[i];
        if(par[i]) graph[par[i]].push_back(i);
        else root = i;
    }

    dfs(root);

    if(n <= 20) {
        int ans = 0;

        for(int s=0; s<(1<<n); s++) {
            if(__builtin_popcount(s) != m) continue;
            int res = 0, ok = 1;
            vector<int> vec;
            for(int i=0; i<n; i++)
                if(s & (1 << i)) vec.push_back(i+1), res += val[i+1];
            for(int i=0; i<vec.size(); i++)
                for(int j=i+1; j<vec.size(); j++)
                    if(anc(vec[i], vec[j]) || anc(vec[j], vec[i])) ok = 0;
            if(ok) ans = max(ans, res);
        }

        cout << ans << '\n';
        return 0;
    }

    for(int i=n-1; i>=0; i--) {
        for(int j=0; j<=m; j++) {
            dp[i][j] = max(dp[i+1][j], dp[out[euler[i]]+1][j]);
            if(j) dp[i][j] = max(dp[i][j], dp[out[euler[i]]+1][j-1] + val[euler[i]]);
        }
    }

    cout << dp[1][m] << '\n';
    return 0;
}

Compilation message (stderr)

biochips.cpp: In function 'int main()':
biochips.cpp:39:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |             for(int i=0; i<vec.size(); i++)
      |                          ~^~~~~~~~~~~
biochips.cpp:40:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |                 for(int j=i+1; j<vec.size(); j++)
      |                                ~^~~~~~~~~~~

• Subtask 1: 90 / 100