51Nod 1174 区间中最大的数(RMQ)

 #include <iostream>
 #include <algorithm>
 #include <cstring>

 using namespace std;
 const int maxn =  + ;
 int a[maxn];
 int f[maxn][];

 void rmq(int cnt){
     memset(f, , sizeof(f));
     for (int i = ; i <= cnt; i++){
         f[i][] = a[i];
     }

     //O(nlogn)
     for (int j = ; j < ; j++){
         for (int i = ; i <= cnt; i++){
             if (i + ( << j) -  <= cnt){
                 f[i][j] = max(f[i][j - ], f[i + ( << (j - ))][j - ]);
             }
         }
     }
 }

 int Query(int x, int y){
     int k = ;
     while (( << (k + )) <= y - x + )
         k++;
     return max(f[x][k], f[y - ( << k) + ][k]);
 }

 int main(){
     ios::sync_with_stdio(false);

     int n;
     cin >> n;
     for (int i = ; i <= n; i++){
         cin >> a[i];
     }
     rmq(n);
     int m;
     cin >> m;
     while (m--){
         int x, y;
         cin >> x >> y;
         x++, y++;
         int ans = Query(x, y);
         cout << ans << endl;
     }

     //system("pause");
     return ;
 }