Cod sursa(job #1823948)

Utilizator retrogradLucian Bicsi retrograd Data 7 decembrie 2016 00:06:56
Problema Range minimum query Scor 40
Compilator cpp Status done
Runda Arhiva educationala Marime 1.2 kb
#include <bits/stdc++.h>

using namespace std;

vector<int> Link;
int Find(int x) {
    if(Link[x] != -1)
        return Link[x] = Find(Link[x]);
    return x;
}
struct Query {
    int a, b, i;
};

int main() {
    freopen("rmq.in", "r", stdin);
    freopen("rmq.out", "w", stdout);
    
    int n, m;
    cin >> n >> m;
    
    vector<int> Val(n), Ans(m);
    for(auto &v : Val)
        cin >> v;
    
    vector<Query> Qs(m);
    int at = 0;
    for(auto &p : Qs) {
        cin >> p.a >> p.b;
        p.a--;
        p.i = at++;
    }
    
    Link.resize(n, -1);
    
    // Sort
    vector<int> Cnt(n + 1, 0);
    for(auto &p : Qs)
        Cnt[p.b] += 1;

    int acc = 0;
    for(auto &x : Cnt)
        x = (acc += x);
    
    vector<Query> Srt(m);
    reverse(Qs.begin(), Qs.end());
    for(auto &q : Qs)
        Srt[--Cnt[q.b]] = q;
    
    vector<int> St;
    at = 0;
    for(auto &q : Srt) {
        while(at < q.b) {
            while(!St.empty() && Val[St.back()] >= Val[at]) {
                Link[St.back()] = at;
                St.pop_back();
            }
            St.push_back(at++);
        }
        Ans[q.i] = Val[Find(q.a)];
    }
    
    for(auto &a : Ans)
        cout << a << '\n';
    
    return 0;
}