线段树求区间最大值与最小值的差

#include <cmath>
#include<stdio.h>
#include<string.h>
#include<iostream>
using namespace std;
#define L(x) (x << 1)
#define R(x) (x << 1 | 1)
#define INT_MAX 0x7fffffff
const int MAX = 50010;
struct Tnode
{
int mmax,mmin,val;
int l,r;
};
Tnode node[MAX*3];
int v[MAX],big,small;
void init()
{
memset(node,0,sizeof(node));
}
void build(int t,int l,int r)
{
node[t].l=l;
node[t].r=r;
if(l==r-1)
{
node[t].mmin=v[l];
node[t].mmax=v[l];
return ;
}
int mid =(l+r)>>1;
build(L(t),l,mid);
build(R(t),mid,r);
node[t].mmax=max(node[L(t)].mmax,node[R(t)].mmax);
node[t].mmin=min(node[L(t)].mmin,node[R(t)].mmin);
}
void get(int t,int l,int r)
{
if(node[t].l==l&&node[t].r==r)
{
big=max(node[t].mmax,big);
small=min(node[t].mmin,small);
return ;
}
int mid=(node[t].l+node[t].r)>>1;
if(l>=mid)
get(R(t),l,r);
else if(r<=mid)
get(L(t),l,r);
else
{
get(R(t),mid,r);
get(L(t),l,mid);
}
}
int main()
{
int n,m,x,y;
while( ~scanf("%d%d",&n,&m))
{
init();
for(int i=1; i<=n; i++)
scanf("%d",&v[i]);
build(1,1,n+1);
while(m--)
{
scanf("%d%d",&x,&y);
small=INT_MAX; big=0;
get(1,x,y+1);
printf("%d\n",big-small);
}
}
return 0;
}