RMQ算法

#include <iostream>
#include <cmath>
#define maxn 10005
using namespace std;
int maxsum[maxn][20], minsum[maxn][20];

void RMQ(int num)    //预处理->O(nlogn)  
{
    int i, j;
    for(j = 1; j < 20; ++j)
      for(i = 1; i <= num; ++i)
      if(i + (1 << j) -1 <= num)
      {
          maxsum[i][j] = max(maxsum[i][j-1], maxsum[i+(1 << j)][j-1]);
          minsum[i][j] = min(minsum[i][j-1], minsum[i+(1 << j)][j-1]);
        }
}

int main()
{
    int i, j, num, t, query;
    cin >> t;
    while(t--)
    {
        cin >> num >> query;
        for(i = 0; i < num; i++)
        {
            cin >> maxsum[i][0];
            minsum[i][0] = maxsum[i][0];
        }
        RMQ(num);
        int start, end, maxl, minl;
        while(query--) //o(1) 查询
        {
            cin >> start >> end;
            int k = (int)((log(end-start+1))/log(2.0));
            maxl = max(maxsum[start][k], maxsum[end-(1 << k)+1][k]);
            minl = min(minsum[start][k], minsum[end-(1 << k)+1][k]);
            cout << maxl << minl << endl;
        }
    }
    return 0;
}