线段树解法
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <climits>
using namespace std;
const int N = 1e5+10;
int n,m;
int w[N];
struct Node{
int l,r;
int maxv;
}tr[4*N];
int pushup(int u)
{
tr[u].maxv = max(tr[u<<1].maxv, tr[u<<1|1].maxv);
}
void build(int u, int l, int r)
{
if(l == r) tr[u]={l,r,w[r]};
else{
tr[u]={l,r};
int mid=l+r>>1;
build(u<<1, l, mid),build(u<<1|1, mid+1, r);
pushup(u);
}
}
int query(int u, int l, int r)
{
if(tr[u].l>=l&&tr[u].r<=r) return tr[u].maxv;
int mid = tr[u].l + tr[u].r >> 1;
int sum= INT_MIN;
if(l<=mid) sum = query(u<<1, l, r);
if(r>mid) sum = max(sum, query(u<<1|1, l, r));
return sum;
}
int main()
{
scanf("%d%d",&n,&m);
for(int i=1; i<=n; i++) scanf("%d",&w[i]);
build(1,1,n);
while( m-- )
{
int x,y;
scanf("%d%d",&x,&y);
printf("%d\n",query(1, x, y));
}
return 0;
}