Submission #871041

#	Time	Username	Problem	Language	Result	Execution time	Memory
871041		Theo830	Fountain (eJOI20_fountain)	C++17	100 / 100	360 ms	31372 KiB

fountain

#include <bits/stdc++.h>
using namespace std;
#define ii pair<int,int>
vector<vector<int> >adj;
const int N = 1e5 + 5;
const int K = 18; /// K = log2N
int d[N],c[N];
int lift[N][K];
int sum[N][K];
void dfs(int idx,int p){
    lift[idx][0] = p;
    sum[idx][0] = c[idx];
    for(int j = 1;j < K;j++){
        lift[idx][j] = lift[lift[idx][j-1]][j-1];
        sum[idx][j] = sum[idx][j-1] + sum[lift[idx][j-1]][j-1];
    }
    for(auto x:adj[idx]){
        if(x != p){
            dfs(x,idx);
        }
    }
}
int main(void){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n,q;
    cin>>n>>q;
    adj.assign(n+5,vector<int>());
    for(int i = 1;i <= n;i++){
        cin>>d[i]>>c[i];
    }
    stack<ii>s;
    for(int i = n;i >= 1;i--){
        while(!s.empty() && s.top().first <= d[i]){
            s.pop();
        }
        if(s.empty()){
            adj[i].push_back(0);
            adj[0].push_back(i);
        }
        else{
            adj[i].push_back(s.top().second);
            adj[s.top().second].push_back(i);
        }
        s.push(ii(d[i],i));
    }
    dfs(0,0);
    while(q--){
        int r,v;
        cin>>r>>v;
        for(int j = K-1;j >= 0;j--){
            if(sum[r][j] < v){
                v -= sum[r][j];
                r = lift[r][j];
            }
        }
        cout<<r<<endl;
    }
}

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40