要求区间取min和max，可以用st表或线段树维护
st表

#include<iostream>
#include<cstdio>
using namespace std;
const int N=100005;
int n,q,b[N],mn[N][20],mx[N][20];
int read()
{int r=0,f=1;char p=getchar();while(p>'9'||p<'0'){if(p=='-')f=-1;p=getchar();}while(p>='0'&&p<='9'){r=r*10+p-48;p=getchar();}return r*f;
}
int maxx(int l,int r)
{int k=b[r-l+1];return max(mx[l][k],mx[r-(1<<k)+1][k]);
}
int minn(int l,int r)
{int k=b[r-l+1];return min(mn[l][k],mn[r-(1<<k)+1][k]);
}
int main()
{n=read(),q=read();for(int i=1;i<=n;i++)mn[i][0]=mx[i][0]=read();for(int i=2;i<=n;i++)b[i]=b[i>>1]+1;for(int j=1;(1<<j)<=n;j++)for(int i=1;i<=n;i++)mn[i][j]=min(mn[i][j-1],mn[i+(1<<(j-1))][j-1]);for(int j=1;(1<<j)<=n;j++)for(int i=1;i<=n;i++)mx[i][j]=max(mx[i][j-1],mx[i+(1<<(j-1))][j-1]);while(q--){int x=read(),y=read();printf("%d\n",maxx(x,y)-minn(x,y));}return 0;
} 

线段树

#include<iostream>
#include<cstdio>
using namespace std;
const int N=100005;
int n,q,a[N];
struct tree
{int l,r,mi,ma;
}t[N<<1];
int read()
{int r=0,f=1;char p=getchar();while(p>'9'||p<'0'){if(p=='-')f=-1;p=getchar();}while(p>='0'&&p<='9'){r=r*10+p-48;p=getchar();}return r*f;
}
void build(int ro,int l,int r)
{t[ro].l=l,t[ro].r=r;if(l==r){t[ro].mi=a[l];t[ro].ma=a[l];}else{int mid=(l+r)>>1;build(ro<<1,l,mid);build(ro<<1|1,mid+1,r);t[ro].ma=max(t[ro<<1].ma,t[ro<<1|1].ma);t[ro].mi=min(t[ro<<1].mi,t[ro<<1|1].mi);}
}
int maxx(int ro,int l,int r)
{if(t[ro].l==l&&t[ro].r==r)return t[ro].ma;int mid=(t[ro].l+t[ro].r)>>1;if(r<=mid)return maxx(ro<<1,l,r);else if(l>mid)return maxx(ro<<1|1,l,r);elsereturn max(maxx(ro<<1,l,mid),maxx(ro<<1|1,mid+1,r));
}
int minn(int ro,int l,int r)
{if(t[ro].l==l&&t[ro].r==r)return t[ro].mi;int mid=(t[ro].l+t[ro].r)>>1;if(r<=mid)return minn(ro<<1,l,r);else if(l>mid)return minn(ro<<1|1,l,r);elsereturn min(minn(ro<<1,l,mid),minn(ro<<1|1,mid+1,r));
}
int main()
{n=read(),q=read();for(int i=1;i<=n;i++)a[i]=read();build(1,1,n);while(q--){int x=read(),y=read();printf("%d\n",maxx(1,x,y)-minn(1,x,y));}return 0;
}