Cod sursa(job #3222760)

Utilizator Programator060804Ungureanu Vlad Constantin Programator060804 Data 11 aprilie 2024 16:23:43
Problema Range minimum query Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.54 kb
#include <bits/stdc++.h>
#include <fstream>
using namespace std;

const int NMAX = 1e5;
int a[NMAX + 1];
int rmq[NMAX + 1][18], LOG[NMAX + 1];

//query in O(1), functioneaza doar pentru functii idempotente
int query1(int x, int y) {
    int k = LOG[y - x + 1];
    return min(rmq[x][k], rmq[y - (1 << k) + 1][k]);
}

//query in O(log(n)), merge si pe functii neidempotente
int query2(int x, int y) {
    int diff = y - x + 1;
    int st = x;
    int sol = 1e9;
    for(int i = 0; (1 << i) <= diff; i++) {
        if((1 << i) & diff) {
            sol = min(sol, rmq[st][i]);
            st += (1 << i);
        }
    }
    return sol;
}

int main() {
    //pb1
    ifstream in("rmq.in");
    ofstream out("rmq.out");
    int N, M, x, y;
    in >> N >> M;
    for(int i = 1; i <= N; i++){
        in >> a[i];
    }
    for(int i = 2; i <= N; i++) {
        LOG[i] = LOG[i / 2] + 1;
    }
    for(int i = 1; i <= N; i++) {
        rmq[i][0] = a[i];
    }
    for(int j = 1; (1 << j) <= N; j++) {
        for(int i = 1; i + (1 << j) - 1 <= N; i++) {
            rmq[i][j] = min(rmq[i][j - 1], rmq[i + (1 << (j - 1))][j - 1]);
        }
    }
    for(int i = 1; i <= M; i++){
        in >> x >> y;
        out << query1(x, y) << '\n';
    }
    return 0;
}

// https://infoarena.ro/problema/rmq
// https://www.pbinfo.ro/probleme/1735/divquery
// https://www.pbinfo.ro/probleme/3860/consecutive1
// https://www.infoarena.ro/problema/stramosi
// https://www.infoarena.ro/problema/lca
// https://www.youtube.com/watch?v=0jWeUdxrGm4
// https://www.youtube.com/watch?v=oib-XsjFa-M