Submission #444647

#	Time	Username	Problem	Language	Result	Execution time	Memory
444647		shrimb	Fountain (eJOI20_fountain)	C++17	100 / 100	410 ms	40760 KiB

fountain

#include"bits/stdc++.h"
#define int long long
#define endl '\n'
using namespace std;
pair<int,int> sparse[100001][20]; // {node, capacity}
 
signed main () {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n, q;
    cin >> n >> q;
    for (int i = 1 ; i <= n ; i++) {
        for (int j = 0 ; j < 20 ; j++) sparse[i][j] = {-1, INT_MAX};
    }
    pair<int,int> arr[n + 1];
    vector<pair<int,int>> v; // {radius, index}
    vector<int> E;
    set<int> s;
    for (int i = 1 ; i <= n ; i++) {
        cin >> arr[i].first >> arr[i].second;
        v.push_back({arr[i].first, i});
    }
    sort(v.begin(), v.end());
 
    for (int i = n - 1 ; i >= 0 ; i--) {
        auto it = s.lower_bound(v[i].second);
        sparse[v[i].second][0] = {(it == s.end() ? -1 : *it), arr[v[i].second].second};
        E.push_back(v[i].second);
        // s.insert(v[i].second);
        if (i == 0 || v[i].first != v[i-1].first) {
            for (int j : E) s.insert(j);
            E.clear();
        }
    }
 
    for (int i = n ; i >= 1 ; i--) {
        for (int j = 1 ; sparse[i][j-1].first != -1 ; j++) {
            sparse[i][j] = {sparse[sparse[i][j-1].first][j-1].first, sparse[i][j-1].second + sparse[sparse[i][j-1].first][j-1].second};
        }
    }
 
    while (q--) {
        int s, x;
        cin >> s >> x;
        for (int i = 19 ; i >= 0 ; i--) {
            if (sparse[s][i].second < x) {
              x -= sparse[s][i].second;
                s = sparse[s][i].first;
                
            }
        }
        cout << (s == -1 ? 0 : s) << endl;
    }
}
//    5   4
// 1 -> 2 -> 3

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