51nod 1174 1174 区间中最大的数

题目链接：51nod 1174 1174 区间中最大的数

ST（Sparse Table）算法学习参考博客：http://blog.csdn.net/niushuai666/article/details/6624672

O(nlogn)预处理，O(1)查询

 #include<cstdio>
 #include<algorithm>
 #include<cmath>
 using namespace std;
 const int N = ;
 int ma[N][];
 int a[N];
 int n;
 void RMQ_init(){
     int i, j;
     for(i = ; i < n; ++i) ma[i][] = a[i];
     int m = (int)(log(n*1.0) / log(2.0));
     for(i = ; i <= m; ++i){
         for(j = ; j < n; ++j){
             ma[j][i] = ma[j][i-];
             if(j + ( << (i-)) <= n)
                 ma[j][i] = max(ma[j][i], ma[j + ( << (i-))][i-]);
         }
     }
 }
 int RMQ_max(int l, int r){
     int m = (int)(log((r-l+)*1.0) / log(2.0));
     return max(ma[l][m], ma[r - ( << m) + ][m]);
 }
 int main(){
     int q, i;
     scanf("%d", &n);
     for(i = ; i < n; ++i) scanf("%d", &a[i]);
     RMQ_init();
     scanf("%d", &q);
     int l, r;
     while(q--){
         scanf("%d%d", &l, &r);
         printf("%d\n", RMQ_max(l, r));
     }
     return ;
 }