数据结构：ST表（可维护区间RMQ）

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
using namespace std;
const int maxn=1e5+10;
int a[maxn][30],logg[maxn],bin[maxn];
int i,j,k,m,n,o,p,js,jl,x,y,t,lg;
inline int read()
{
int x=0,f=1;char ch=getchar();
while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}
while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;
}
int my_max(int x,int y){
if(x>y)return(x);
else return(y);
}
int main(){
// freopen("1.out","w",stdout);
scanf("%d%d",&n,&m);
for(int i=1;i<=n;i++) a[i][0]=read();

bin[0]=1;
for(int i=1;i<=30;i++)
bin[i]=bin[i-1]*2;

logg[0]=-1;
for(int i=1;i<=n;i++)
logg[i]=logg[i/2]+1;

for(int i=1;i<=logg[n];i++){
for(int j=1;j<=n;j++){
if(j+bin[i]-1<=n){
a[j][i]=my_max(a[j][i-1],a[j+bin[i-1]][i-1]);
}
}
}

for(int i=1;i<=m;i++){
x=read();y=read();
t=y-x+1;
lg=logg[t];
printf("%d\n",my_max(a[x][lg],a[y-bin[lg]+1][lg]));
}
return 0;
}