ST算法Code：
//#include<bits/stdc++.h>
#include<cstdio>
#include<math.h>
#include<iostream>
#include<queue>
#include<algorithm>
#include<string.h>
using namespace std;
typedef long long LL;const int N=5e4+10;int n,q;
int a[N];
int f1[N][30];
int f2[N][30];void ST()
{for(int i=1;i<=n;i++)f1[i][0]=f2[i][0]=a[i];int nlog=(int)(log(double(n))/log(2.0));for(int j=1;j<=nlog;j++){for(int i=1;i<=n;i++){if(i+(1<<j)-1<=n){f1[i][j]=min(f1[i][j-1],f1[i+(1<<(j-1))][j-1]);f2[i][j]=max(f2[i][j-1],f2[i+(1<<(j-1))][j-1]);}}}
}
int RMQ(int l,int r)
{int nlog=(int)(log(double(r-l+1))/log(2.0));int mi=min(f1[l][nlog],f1[r-(1<<nlog)+1][nlog]);int ma=max(f2[l][nlog],f2[r-(1<<nlog)+1][nlog]);return ma-mi;
}int main()
{int l,r;while(scanf("%d%d",&n,&q)!=EOF){for(int i=1;i<=n;i++)scanf("%d",&a[i]);ST();while(q--){scanf("%d%d",&l,&r);printf("%d\n",RMQ(l,r));}}return 0;
}
线段树Code：
#include<cstdio>
#include<iostream>
#include<string.h>
#include<algorithm>
using namespace std;const int N=50007;
struct st{int left,right;int mina;int maxa;
};
st q[N*4];
int n,m;void build(int num,int L,int R)
{q[num].left=L;q[num].right=R;if(L==R){scanf("%d",&q[num].maxa);q[num].mina=q[num].maxa;return;}build(2*num,L,(L+R)/2);build(2*num+1,(L+R)/2+1,R);q[num].mina=min(q[2*num].mina,q[2*num+1].mina);q[num].maxa=max(q[2*num].maxa,q[2*num+1].maxa);
}
int ans1;
int ans2;
int get_max(int num,int s,int t)
{if(q[num].left>=s&&q[num].right<=t)return q[num].maxa;int mid=(q[num].left+q[num].right)/2;if(mid>=t)return get_max(2*num,s,t);else if(mid<s)return get_max(2*num+1,s,t);else{return max(get_max(2*num,s,mid),get_max(2*num+1,mid+1,t));}
}int get_min(int num,int s,int t)
{if(q[num].left>=s&&q[num].right<=t)return q[num].mina;int mid=(q[num].left+q[num].right)/2;if(mid>=t)return get_min(2*num,s,t);else if(mid<s)return get_min(2*num+1,s,t);else{return min(get_min(2*num,s,mid),get_min(2*num+1,mid+1,t));}
}int main()
{scanf("%d%d",&n,&m);build(1,1,n);while(m--){int a,b;scanf("%d%d",&a,&b);printf("%d\n",get_max(1,a,b)-get_min(1,a,b));}return 0;
}
