[hackerrank]Service Lane

https://www.hackerrank.com/challenges/service-lane

用RMQ做的，其实暴力也能过~

#include <iostream>

#include <vector>

#include <cmath>

using namespace std;



int main() {

    int n, t;

    cin >> n >> t;

    vector<int> vec(n);

    for (int i = 0; i < n; i++) {

        cin >> vec[i];

    }

    vector<vector<int>> m(n);

    for (int i = 0; i < n; i++) {

        m[i].resize(10);

    }

    

    for (int d = 0; d < 10; d++) {

        for (int i = 0; i < n; i++) {

            if (d == 0) {

                m[i][d] = vec[i];

            } else {

                m[i][d] = m[i][d - 1];

                int subd = (int)pow(2, d - 1);

                int j = i + subd;

                if (j + subd <= n)

                    m[i][d] = min(m[i][d - 1], m[j][d - 1]);

            }

        }

    }

    while (t--) {

        int a, b;

        cin >> a >> b;

        int diff = (b - a + 1);

        int d = 0;

        int len = 1;

        for (; len <= diff; len*=2, d++);

        d--;

        len /= 2;

        int x = min(m[a][d], m[b - len + 1][d]);

        cout << x << endl;

    }

    return 0;

}