[线段树] *求区间最大值减最小值*

题目

题目链接：https://vjudge.net/contest/357681#problem/H

思路

普通线段树，用max,min记录一下最小值最大值就好了

代码

#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<cctype>
#include<ctime>
#include<iostream>
#include<string>
#include<map>
#include<queue>
#include<stack>
#include<set>
#include<vector>
#include<iomanip>
#include<list>
#include<bitset>
#include<sstream>
#include<fstream>
#include<complex>
#include<algorithm>
#if __cplusplus >= 201103L
#include <unordered_map>
#include <unordered_set>
#endif
#define ll long long
using namespace std;
const int INF = 0x3f3f3f3f;
const int maxn=50010;
struct sut{
	int l,r,mmin,mmax; 
	bool lazy;
}tree[maxn<<2];
int a[maxn];
void build(int l1,int r1,int x){
	tree[x].l=l1,tree[x].r=r1,tree[x].lazy=0;
	if(l1==r1){
		tree[x].mmax=a[l1];
		tree[x].mmin=a[l1];
		return; 
	}
	int mid=(l1+r1)>>1;
	build(l1,mid,x<<1);
	build(mid+1,r1,x<<1|1);	
	tree[x].mmin=min(tree[x<<1|1].mmin,tree[x<<1].mmin);
	tree[x].mmax=max(tree[x<<1|1].mmax,tree[x<<1].mmax);	
///	tree[x].mmax=max(tree[x].lazy,tree[x<<1|1].mmax);
}
int MAX,MIN;
void query(int l1,int r1,int x){
	if(l1<=tree[x].l&&tree[x].r<=r1){
		MAX=max(MAX,tree[x].mmax);
		MIN=min(MIN,tree[x].mmin);
		return;
	}
	int mid=(tree[x].l+tree[x].r)>>1;
	if(l1<=mid) query(l1,r1,x<<1);
	if(r1>mid) query(l1,r1,x<<1|1);
}
int main(){
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	int n,m;
	cin>>n>>m;
	for(int i=1;i<=n;i++) cin>>a[i];
	build(1,n,1);
	while(m--){
		int c,d;
		cin>>c>>d;
		MAX=0,MIN=INF;
		query(c,d,1);
		cout<<MAX-MIN<<endl;
	}
    return 0;
}