C++ :

#include<iostream>
#include<cstring>
#include<cmath>
using namespace std;
int a[100000];
void quicksort(int left,int right)	//快速排序
{
	int i,j,x;
	i=left; j=right;
	x=a[(i+j)/2];
	while (i<=j)
	{
		while (a[i]>x) i++;
		while (a[j]<x) j--;
		if (i<=j)
		{
			int t=a[i]; a[i]=a[j]; a[j]=t;
			i++; j--;
		}
	}
	if (left<j) quicksort(left,j);
	if (i<right) quicksort(i,right);
}
int main()
{
	int n,x;
	cin>>n;
	for (int i=1; i<=n; i++)
	{
		memset(a,0,sizeof(a));
		cin>>x;
		for (int i=1; i<=x; i++) cin>>a[i];
		quicksort(1,x);
		cout<<abs(a[2]-a[x-1])<<endl;
	}
	return 0;
}