Cod sursa(job #2742612)

Utilizator Asgari_ArminArmin Asgari Asgari_Armin Data 21 aprilie 2021 12:09:26
Problema Range minimum query Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.8 kb
#include <bits/stdc++.h>

using namespace std;

ifstream fin( "rmq.in" );
ofstream fout( "rmq.out" );

template<typename T> struct rmq {
	vector<T> v;
	int n; static const int b = 30;
	vector<int> mask, t;

  void reset(const vector<T>& v_) {
    v = v_;
    n = v.size();
    mask = n;
    t = n;
		for (int i = 0, at = 0; i < n; mask[i++] = at |= 1) {
			at = (at<<1)&((1<<b)-1);
			while (at and op(i, i-msb(at&-at)) == i) at ^= at&-at;
		}
		for (int i = 0; i < n/b; i++) t[i] = small(b*i+b-1);
		for (int j = 1; (1<<j) <= n/b; j++) for (int i = 0; i+(1<<j) <= n/b; i++)
			t[n/b*j+i] = op(t[n/b*(j-1)+i], t[n/b*(j-1)+i+(1<<(j-1))]);
	}

	int op(int x, int y) { return v[x] < v[y] ? x : y; }
	int msb(int x) { return __builtin_clz(1)-__builtin_clz(x); }
	int small(int r, int sz = b) { return r-msb(mask[r]&((1<<sz)-1)); }
	rmq(const vector<T>& v_) : v(v_), n(v.size()), mask(n), t(n) {
		for (int i = 0, at = 0; i < n; mask[i++] = at |= 1) {
			at = (at<<1)&((1<<b)-1);
			while (at and op(i, i-msb(at&-at)) == i) at ^= at&-at;
		}
		for (int i = 0; i < n/b; i++) t[i] = small(b*i+b-1);
		for (int j = 1; (1<<j) <= n/b; j++) for (int i = 0; i+(1<<j) <= n/b; i++)
			t[n/b*j+i] = op(t[n/b*(j-1)+i], t[n/b*(j-1)+i+(1<<(j-1))]);
	}
	T query(int l, int r) {
		if (r-l+1 <= b) return v[small(r, r-l+1)];
		int ans = op(small(l+b-1), small(r));
		int x = l/b+1, y = r/b-1;
		if (x <= y) {
			int j = msb(y-x+1);
			ans = op(ans, op(t[n/b*j+x], t[n/b*j+y-(1<<j)+1]));
		}
		return v[ans];
	}
};

int main(){
    using X1 = rmq<int>;
    int n, q, i, x, y;
    fin >> n >> q;
    vector <int> a(n + 1);
    for( i = 1; i <= n; ++i ){
      fin >> x;
      a[i] = x;
    }
    X1 pl(a);
    while( q-- ){
      fin >> x >> y;
      fout << pl.query(x, y) << "\n";
    }
    return 0;
}