find missing and repeating

/*
Given an unsorted array of size N of positive integers. One number 'A' from set {1, 2, …N} is missing and one number 'B' occurs twice in 
array. Find these two numbers.

Note: If you find multiple answers then print the Smallest number found. Also, expected solution is O(n) time and constant extra space.

Input:
The first line of input contains an integer T denoting the number of test cases. The description of T test cases follows. The first line 
of each test case contains a single integer N denoting the size of array. The second line contains N space-separated integers A1, A2, ..., 
AN denoting the elements of the array.

Output:
Print B, the repeating number followed by A which is missing in a single line.

Constraints:
1 ≤ T ≤ 100
1 ≤ N ≤ 106
1 ≤ A[i] ≤ N

Example:
Input:
2
2
2 2
3 
1 3 3

Output:
2 1
3 2

Explanation:
Testcase 1: Repeating number is 2 and smallest positive missing number is 1.
Testcase 2: Repeating number is 3 and smallest positive missing number is 2.
*/

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

int main() {
	int t; cin>>t;
	while(t--){
	    int n,rep,miss; cin>>n;
	    int h[n+1]={0};
	    for(int i=0; i<n; i++){
	        int a;
	        cin>>a;
	        h[a]++;
	    }
	    for(int i=1; i<=n; i++){
	        if(h[i]==2) {
	            rep=i;
	        }
	        if(h[i]==0){
	            miss=i;
	        }
	    }
	    cout<<rep<<" "<<miss<<endl;
	}
	return 0;
}