Missing_and_repeating_numbers.cpp

#include <bits/stdc++.h>

pair<int, int> missingAndRepeating(vector<int> &arr, int n)
{

    unordered_set<int> vis;

    int missing = 0;

    int repeated = 0;

    for (int &num : arr)
    {

        if (vis.count(num))
        {

            repeated = num;
        }
        else
        {

            vis.insert(num);
        }
    }

    for (int num = 1; num <= n; num++)
    {

        if (vis.count(num) == 0)
        {

            missing = num;

            break;
        }
    }

    return {missing, repeated};
}