vector<int> findMissingRepeatingNumbers(vector < int > a) {
    // Write your code here
    
    int n = a.size();
    int xr=0 ,one = 0 , zero = 0;

    for (int i = 0 ; i<n ; ++i){
        xr = xr ^ a[i] ^ (i+1);
    }

    int bit_no = 0;
    while (1){
        if ((xr & (1<<bit_no)) != 0)
            break;

        bit_no++;
    }

    for (int i = 0 ; i<n ;++i ){
        if ((a[i] & (1<<bit_no)) != 0)
            one = one ^ a[i];
            
        else {
            zero = zero ^ a[i];    
        }
        
        if (((i+1) & (1<<bit_no)) != 0)
            one ^= i+1;
        else
            zero ^= i+1;
    }
    
    int cnt = 0;
    for (int i = 0 ; i<n ; ++i){
        if (one == a[i]){
            cnt++;
            if (cnt == 2){
                return {one , zero};
            }
        }
    }
    return {zero , one};
}