在本地测了一下样例，感觉非常amazing，一交就裂开了……

#include <bits/stdc++.h>
#define ll long long
using namespace std;
int T, n;
inline ll read() {
	ll k = 0, f = 1;
	char ch = getchar();
	while ( ch < '0' || ch > '9' ) {
		if ( ch == '-' ) f = -1;
		ch = getchar();
	}
	while ( ch >= '0' && ch <= '9' ) {
		k = k * 10 + ( ch - '0' );
		ch = getchar();
	}
	return k * f;
}
inline ll write ( ll x ) {
	if ( x < 0 ) putchar ( '-' ), x = -x;
	if ( x > 9 ) write ( x / 10 );
	putchar ( x % 10 + '0' );
}
struct node {
	ll number, cont;
} s[500005];
bool cmp1 ( node a, node b ) {
	return a.number < b.number;
}
bool cmp2 ( node a, node b ) {
	return a.cont < b.cont;
}
int main () {
	//	freopen(".in","r",stdin);
	//	freopen(".out","w",stdout);
	cin >> T;
	while ( T-- ) {
		cin >> n;
        	//离散化
		for ( int i = 1; i <= n; i++ ) {
			s[i].number = read(), s[i].cont = i;
		}
		sort(s+1,s+1+n,cmp1);
		for(int i=1;i<=n;i++){
			if(s[i].number==s[i-1].number) s[i].cont=9000000;
		}
		sort(s+1,s+1+n,cmp2);
		for(int i=1;i<=n;i++){
			if(s[i].cont==9000000) break;
			write(s[i].number);putchar(' ');
		}
	}
	return 0;
}