线段树 区间最大最小值 模板

#include<bits/stdc++.h>
using namespace std;
#define int long long

const int N=4e6+10;
const int M=3e4+3e3;
int n,t,m;
char c;
int a[N],max_a[N],min_a[N],sum1[N],sum2[N];

void push(int x)
{
	max_a[x]=max(max_a[x<<1],max_a[x<<1|1]);
	min_a[x]=min(min_a[x<<1],min_a[x<<1|1]);
	sum1[x]=sum1[x*2]+sum1[x*2+1];
}

void build(int l,int r,int k)
{
	if(l==r)
	{
		max_a[k]=a[l];
		min_a[k]=max_a[k];
	}
	else
	{
		int mid=(l+r)/2;
		build(l,mid,k*2);
		build(mid+1,r,k*2+1);
		push(k);
	}
}

int query1(int x,int y ,int k,int l,int r)//求取最大值
{
	if(x<=l&&y>=r)
	return max_a[k];
	int mid=(l+r)/2;
	int ans=-0x7f7f7f7f;
	if(x<=mid)
	ans=max(ans,query1(x,y,k*2,l,mid));
	if(y>mid)
	ans=max(ans,query1(x,y,k*2+1,mid+1,r));
	return ans;
}

int query2(int x,int y ,int k,int l,int r)//求取最小值
{
	if(x<=l&&y>=r)
	return min_a[k];
	int mid=(l+r)>>1;
	int ans=0x7f7f7f7f;
	if(x<=mid)
	ans=min(ans,query2(x,y,k<<1,l,mid));
	if(y>mid)
	ans=min(ans,query2(x,y,k<<1|1,mid+1,r));
	return ans;
}

signed main()
{
	cin>>n>>m;
	for(int i=1;i<=n;i++)
	cin>>a[i];
	build(1,n,1);
	while(m--)
	{
		int x,y;
		cin>>x>>y;
		cout<<query1(x,y,1,1,n)-query2(x,y,1,1,n)<<endl;;
	}
}