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题面
给定给定含n个数的数组A[N],求区间[L,R]的和
数组个数为n,q次查询区间l,r; -
数据范围
#define ll long long
#define lc num<<1
#define rc num<<1|1
#define N 100001
#include<bits/stdc++.h>
using namespace std;
int n,l,r,q;
ll a[N];
struct node{
int l,r,num;
ll val,add;
}tre[N*4];
void pushup(int num)
{
tre[num].val=max(tre[lc].val,tre[rc].val);
}
void build_tre(int l,int r,int num)
{
tre[num].l=l;tre[num].r=r;
if(l==r)
{
tre[num].val=a[l];
return ;
}
int mid=(tre[num].l+tre[num].r)>>1;
build_tre(l,mid,lc);
build_tre(mid+1,r,rc);
pushup(num);
}
ll query_itv(int l,int r,int num)
{
ll ans=-0x3f;
if(tre[num].l>=l&&tre[num].r<=r)
{
return tre[num].val;
}
int mid=(tre[num].l+tre[num].r)>>1;
if(l<=mid) ans=max(ans,query_itv(l,r,lc));
if(r>mid) ans=max(ans,query_itv(l,r,rc));
return ans;
}
signed main()
{
scanf("%d",&n);
for(int i=1;i<=n;i++)
{
scanf("%lld",&a[i]);
}
build_tre(1,n,1);
// cout<<tre[1].val;
scanf("%d",&q);
while(q--)
{
scanf("%d %d",&l,&r);
printf("%lld\n",query_itv(l,r,1));
}
return 0;
}