#include<iostream>
#include<stdio.h>
#include<math.h>
using namespace std;
int n,m,fx[200007][35],fn[200007][35],x,y;
int check(int l,int r){
	int k=log2(r-l+1);
	//cout<<endl<<max(fx[l][k],fx[r-(1<<k)+1][k])<<" "<<min(fn[l][k],fn[r-(1<<k)+1][k])<<endl;
	return max(fx[l][k],fx[r-(1<<k)+1][k])-min(fn[l][k],fn[r-(1<<k)+1][k]);
}
int main(){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++){
		scanf("%d",&fx[i][0]);
		fn[i][0]=fx[i][0];
	}
	for(int i=1;(1<<i)<=n;i++)
		for(int j=1;j<=n-(1<<1)+1;j++)
			fx[j][i]=max(fx[j][i-1],fx[j+(1<<(i-1))][i-1]),
			fn[j][i]=min(fn[j][i-1],fn[j+(1<<(i-1))][i-1]);
	for(int i=1;i<=m;i++){
		scanf("%d%d",&x,&y);
		printf("%d\n",check(x,y));
	}
	/*
	cout<<"\n\n\n\n\n\n\n";
	for(int i=1;i<=n;i++,cout<<endl)
		for(int j=1;j<=20;j++)
			cout<<fx[i][j]<<" ";
			
	cout<<"\n\n\n\n\n\n\n";
	for(int i=1;i<=n;i++,cout<<endl)
		for(int j=1;j<=20;j++)
			cout<<fn[i][j]<<" ";
			*/
	return 0;
}

这是AC代码，原来2,7,8,9,10RE了，之前的代码是fx，fn都开了50007,25，神奇RE，改了以后好了

没弄明白原因，哪位神犇理解的话告诉我一下谢谢