Cod sursa(job #2332852)

Utilizator paniniPanayiotis Panayiotou panini Data 31 ianuarie 2019 12:42:25
Problema Range minimum query Scor 40
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.4 kb
// #include <iostream>
#include <vector>
#include <algorithm>
#include <fstream>
#include <cmath>
#define pii pair<int, int>
#define vec vector
#define MAXNn 100001

using namespace std;

void testcase() {
  ifstream cin("rmq.in");
  ofstream cout("rmq.out");
  int n, m;
  cin >> n >> m;
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  // fast floor log calculation
  vector<int> logOf(n + 1);
  logOf[0] = 0;
  logOf[1] = 0;
  for (int i = 2; i <= n; i++) {
    logOf[i] = logOf[i / 2] + 1;
  }

  int biggestPower = logOf[n];
  vec<vec<int> > rmq(n, vec<int>(biggestPower + 1)); // [from][dist] for 2^dist
  for (int i = 0; i < n; i++) rmq[i][0] = a[i];

  for (int pow2 = 1; pow2 <= biggestPower; pow2++) {
    for (int from = 0; from < n; from++) {
      rmq[from][pow2] = rmq[from][pow2 - 1];
      int next = from + (1 << (pow2 - 1));
      if (next >= n) break; // adev
      auto candidate = rmq[next][pow2 - 1];
      if (candidate <  rmq[from][pow2]) rmq[from][pow2] = candidate;
    }
  }

  // answer the queries in O(1)
  int from, to;
  for (int i = 0; i < m; i++) {
    cin >> from >> to;
    --from; --to;
    int dist = to - from + 1;
    int logDist = logOf[dist];
    cout << min(rmq[from][logDist], rmq[to - (1 << logDist) + 1][logDist]) << endl;
  }
  cin.close();
  cout.close();
}

int main() {
  // ios_base::sync_with_stdio(false);
  // cin.tie(0);
  testcase();
  return 0;
}