Digit longest increasing subsequences 2(cpp)

#include<bits/stdc++.h>
using namespace std;

int main(){
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        for(int i=0;i<n;++i){
            int x; cin>>x;
            cout<<x;
        }
        cout<<endl;
    }
    return 0;
}