【模板】RMQ问题 ST表

洛谷3865

 #include<cstdio>
 #include<algorithm>
 #include<cmath>
 using namespace std;
 const int maxn=;
 int f[maxn][],n,m,l,r;
 void read(int &k){
     k=; int f=; char c=getchar();
     while (c<''||c>'')c=='-'&&(f=-),c=getchar();
     while (''<=c&&c<='')k=k*+c-'',c=getchar();
     k*=f;
 }

 int main(){
     read(n); read(m);
     for (int i=;i<=n;i++) read(f[i][]);
     for (int j=;j<=log2(n);j++)
         for (int i=;i<=n-(<<j)+;i++)
             f[i][j]=max(f[i][j-],f[i+(<<(j-))][j-]);
     for (int i=;i<=m;i++){
         read(l); read(r);
         int k=log2(r-l+);
         printf("%d\n",max(f[l][k],f[r-(<<k)+][k]));
     }
     return ;
 }