Submission #468019

#	Time	Username	Problem	Language	Result	Execution time	Memory
468019		UltraFalcon	Fountain (eJOI20_fountain)	C++17	100 / 100	447 ms	44480 KiB

fountain

#include <bits/stdc++.h>
#define int long long

using namespace std;

const int INF = 1e18;

vector<vector<pair<int, int>>> adj;
vector<vector<pair<int, int>>> par;

void dfs(int v) {
    //cerr << v << " -- v start\n";
    for (auto [u, ci] : adj[v]) {
        par[u][0] = {v, ci};
        dfs(u);
    }
    //cerr << v << " -- v end\n"; 
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n, q;
    cin >> n >> q;

    int log_n = __lg(n-1) + 1;

    //cerr << log_n;

    vector<pair<int, int>> resv; // di, ci
    for (int i=0; i<n; i++) {
        int di, ci;
        cin >> di >> ci;
        resv.push_back({di, ci});
    }
    resv.push_back({INF, INF}); // Add the waterway
    reverse(resv.begin(), resv.end());

    adj.assign(n+1, {});

    vector<int> st; 
    st.push_back(0);
    for (int i=1; i<=n; i++) {
        while (resv[st.back()].first <= resv[i].first) {
            //cerr << st.back() << "\n";
            st.pop_back();
        }
        adj[st.back()].push_back({i, resv[i].second});
        //adj[i].push_back({st.back(), resv[i].second});
        st.push_back(i);
    }

    //cerr << "run1\n";

    // Compute binary lift
    par.assign(n+1, vector<pair<int, int>>(log_n, {-1, INF}));
    dfs(0);

    //cerr << "run2\n";

    for (int k=1; k<log_n; k++) {
        for (int i=1; i<=n; i++) {
            if (par[i][k-1].first < 0) { continue; }
            par[i][k] = {par[par[i][k-1].first][k-1].first, par[i][k-1].second + par[par[i][k-1].first][k-1].second};
            //cerr << par[i][k].first << " ";
        }
        //cerr << "\n";
    }
    
    //cerr << "run3\n";

    //return 0;

    for (int i=0; i<q; i++) {
        int ri, vi;
        cin >> ri >> vi;

        //cerr << "run0" << "\n";
        
        /*
        int lvl = n - ri + 1;
        int vol_sum = 0;
        while (vol_sum+par[lvl][0].second < vi) {
            //cerr << vol_sum+par[lvl][0].second << " -- dbg2\n";
            int pow = 0;
            while (pow < log_n && vol_sum+par[lvl][pow].second < vi) {
                pow++;
            }
            vol_sum += par[lvl][pow-1].second;
            lvl = par[lvl][pow-1].first;
            //cerr << vol_sum+par[lvl][0].second << " -- dbg\n";
        }*/

        int lvl = n - ri + 1;
        int vol_sum = 0;

        for (int pow=log_n-1; pow >= 0; pow--) {
            if (par[lvl][pow].first != -1 && vol_sum+par[lvl][pow].second < vi) {
                vol_sum += par[lvl][pow].second;
                lvl = par[lvl][pow].first;
            }
        }

        //cerr << vol_sum << "\n";
        //cerr << "calc end\n";

        if (lvl == 0) {
            cout << 0 << "\n";
        } else {
            cout << n - lvl + 1 << "\n";
        }
    }

}

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