@[yezihao1](/user/346662)
```
for(int k=1;(1<<k)<=n;k++)
{
for(int i=1;i<=n;i++)
{
f[k][i]=max(f[k-1][i],f[k-1][i+(1<<(k-1))]);
}
}
```
这里给 $i$ 控制一下边界
by y0y68 @ 2022-01-29 17:21:25
@[y0y68](/user/115668) 还是错6个点
```cpp
#include<bits/stdc++.h>
using namespace std;
const int maxn=1e6+5;
int a[maxn];
int f[maxn][21];
int lg[maxn<<1];
inline int read()
{
register int f=0,x=0;register char ch=getchar();
while(ch<'0'||ch>'9')f|=ch=='-',ch=getchar();
while(ch>='0'&&ch<='9')x=(x<<3)+(x<<1)+(ch^48),ch=getchar();
return f?-x:x;
}
inline void write(register int ans,register bool flag)
{
if(ans<0)putchar('-'),ans=-ans;
if(ans==0)
{
if(!flag) putchar('0');
return ;
}
write(ans/10,true);
putchar(ans%10^'0');
}
inline void init()
{
lg[1] = 0;
for (int i = 2 ; i <= 2*maxn ; ++ i) lg[i] = lg[i/2]+1;
}
int main()
{
//freopen("P3865_4.in","r",stdin);
//freopen("P3865_4.out","w",stdout);
init();
int n=read(),m=read();
for(int i=1;i<=n;i++)
{
a[i]=read();
}
for(int i=1;i<=n;i++)
{
f[0][i]=a[i];
}
for(int k=1;(1<<k)<=n;k++)
{
for(int i=1;i+(1<<k)-1<=n;i++)
{
f[k][i]=max(f[k-1][i],f[k-1][i+(1<<(k-1))]);
}
}
for(int i=1;i<=m;i++)
{
int a=read(),b=read();
int len=lg[b-a+1];
write(max(f[len][a],f[len][b-(1<<len)+1]),true);
putchar('\n');
}
return 0;
}
```
by yezihao1 @ 2022-01-29 17:43:12