Cod sursa(job #2779612)

Utilizator bogdanvladmihaiBogdan Vlad-Mihai bogdanvladmihai Data 4 octombrie 2021 14:05:34
Problema Range minimum query Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.36 kb
#include <bits/stdc++.h>

std::ifstream in("rmq.in");
std::ofstream out("rmq.out");

class RMQ {
private:
  int n;
  std::vector<std::vector<int>> rmq;
  std::vector<int> lg;
  std::vector<int> arr;
public:
  RMQ(std::vector<int> _arr) {
    arr = _arr;
    n = (int)arr.size();
    int l = log2((int)arr.size()) + 2;
    rmq.resize(l);
    for (int i = 0; i < (int)rmq.size(); i++) {
      rmq[i].resize(n + 1);
    }
    for (int i = 1; i <= n; i++) {
      rmq[0][i] = i - 1;
    }
    lg.resize(n + 1);
    for (int i = 2; i <= n; i++) {
      lg[i] = 1 + lg[i / 2];
    }
    for (int l = 1; (1 << l) <= n; l++) {
      for (int j = 1; j <= n - (1 << l) + 1; j++) {
        int pw = (1 << (l - 1));
        if (arr[rmq[l - 1][j]] < arr[rmq[l - 1][j + pw]]) {
          rmq[l][j] = rmq[l - 1][j];
        } else {
          rmq[l][j] = rmq[l - 1][j + pw];
        }
      }
    }
  }
  int query(int l, int r) {
    int p = lg[r - l + 1];
    if (arr[rmq[p][l]] < arr[rmq[p][l + (1 << p) - 1]]) {
      return rmq[p][l];
    } else {
      return rmq[p][r - (1 << p) + 1];
    }
  }
};

int n, m;

int main() {
  in >> n >> m;
  std::vector<int> v(n);
  for (int &x : v) {
    in >> x;
  }
  RMQ ds(v);
  for (int i = 1; i <= m; i++) {
    int x, y;
    in >> x >> y;
    out << v[ds.query(x, y)] << "\n";
  }
  return 0;
}