#include <bits/stdc++.h>
using namespace std;
int main() {
int i, j, k;
int t, n;
int a[1000];
cin >> t;
for(k = 0; k < t; k++)
{
cin >> n;
int diff = 0, ans = 100005;
for(j = 0; j < n; j++)
cin >> a[j];
sort(a,a+n);
for(i = 0; i < n-1; i++)
{
diff = a[i+1] - a[i];
ans = min(ans, diff);
}
cout << ans;
}
return 0;
}
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