学步园

本来想刷刷水题，结果刷出问题来了，查询区间自己还是没有彻底弄透，警告！！

#include <iostream>
#include <fstream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <string.h>
#include <vector>
#include <bitset>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <ctime>
#include <map>
#include <limits>
#define LL long long
#define Vi vector<int>
#define Si set<int>
#define readf freopen("input.txt","r",stdin)
#define writef freopen("output.txt","w",stdout)
#define FF(i,a) for(int i(0); i < (a); i++)
#define FD(i,a) for(int i(a); i >= (1); i--)
#define FOR(i,a,b) for(int i(a);i <= (b); i++)
#define FOD(i,a,b) for(int i(a);i >= (b); i--)
#define PD(a) printf("%d",a)
#define SET(a,b) memset(a,b,sizeof(a))
#define SD(a) scanf("%d",&(a))
#define LN printf("\n")
#define PS printf(" ")
#define pb push_back
#define lson l , m , rt << 1
#define rson m + 1 , r , rt << 1 | 1
const double pi = acos(-1.0);
const int maxn = 200001;
const int INF = 99999999;
const int dx[]={0,1,0,-1};
const int dy[]={1,0,-1,0};
using namespace std;
int N,M;
int MAX[maxn<<2],MIN[maxn<<2];
void PushUP(int rt){
    MAX[rt]=max(MAX[rt<<1],MAX[rt<<1|1]);
    MIN[rt]=min(MIN[rt<<1],MIN[rt<<1|1]);
}
void build(int l,int r,int rt){
    if(l==r){
        SD(MAX[rt]);
        MIN[rt]=MAX[rt];
        return ;
    }
    int m=(l+r)>>1;
    build(lson);
    build(rson);
    PushUP(rt);
}
int query1(int L,int R,int l,int r,int rt) {
	if (L <= l && r <= R) {
		return MAX[rt];
	}
	int m = (l + r) >> 1;
	int ret =0;
	if (L <= m) ret = max(ret , query1(L , R , lson));
	if (R > m) ret = max(ret , query1(L , R , rson));
	return ret;
}
int query2(int L,int R,int l,int r,int rt) {
	if (L <= l && r <= R) {
		return MIN[rt];
	}
	int m = (l + r) >> 1;
	int ret = INF;
	if (L <= m) ret = min(ret , query2(L , R , lson));
	if (R > m) ret = min(ret , query2(L , R , rson));
	return ret;
}
void print(int l,int r,int rt){
    printf("l:%d  r:%d   max:%d  min:%d \n",l,r,MAX[rt],MIN[rt]);
    if(l==r)
        return ;
    int m=(l+r)>>1;
    print(lson);
    print(rson);
}
int main()
{
    SD(N);SD(M);
    build(1,N,1);
    FOR(i,1,M){
        int ql,qr;
        SD(ql);SD(qr);
        int maxans=query1(ql,qr,1,N,1);
        int minans=query2(ql,qr,1,N,1);
        printf("%d\n",maxans-minans);
    }
    return 0;
}