Submission #1247928

#	Time	Username	Problem	Language	Result	Execution time	Memory
1247928		quocbaoo	Biochips (IZhO12_biochips)	C++20	100 / 100	1806 ms	401992 KiB

biochips

#include<bits/stdc++.h>
#define fi first
#define se second
#define ll long long
using namespace std;
const int N=2e5,INF=1e9+7;
int bd[N+5];int n,m;int dp[N+5][505],cnt=0,nex[N+5],ke[N+5],a[N+5];
vector<int> g[N+5];
void dfs(int u){
    cnt++;bd[cnt]=u;
    for (auto j:g[u]){
        if (ke[u]==0) ke[u]=j;dfs(j);
    }
    nex[u]=cnt+1;
}
int f(int i,int j){
    if (j>m) return -1e9;
    if (i>n){
        if (j==m) return 0;return -1e9;
    }
    if (dp[i][j]!=-INF) return dp[i][j];
    int ans=-1e9;
    ans=max(ans,f(bd[nex[i]],j));
    ans=max(ans,a[i]+f(bd[nex[i]],j+1));
    if (ke[i]!=0) ans=max(ans,f(ke[i],j));
//    cout<<i<<" "<<a[i]<<endl;
    return dp[i][j]=ans;
}
int main(){
    if (fopen("biochips.inp","r")){
        freopen("biochips.inp","r",stdin);
        freopen("biochips.out","w",stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    cin>>n>>m;
    int cha=1;
    for (int i=1;i<=n;i++){
        int u,x;cin>>u>>x;
        if (u==0) cha=i;
        else g[u].push_back(i);
        a[i]=x;
    }
    for(int i=1;i<=n;i++){
        for (int j=0;j<=m;j++) dp[i][j]=-INF;
    }
    bd[n+1]=n+1;
    dfs(cha);
//    cout<<nex[7]<<endl;
    cout<<f(cha,0);
}

Compilation message (stderr)

biochips.cpp: In function 'int main()':
biochips.cpp:31:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |         freopen("biochips.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
biochips.cpp:32:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |         freopen("biochips.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100