Find the Repeating and Missing Numbers

In this article, we will solve the problem of finding the repeating and missing numbers in a given array of integers using a hash map. So we are given an array of integers in the range [1, N] and each integer in that range appears exactly once except one number which appears twice, and one number which is missing.

Example:

Input: [3, 1, 2, 5, 3]

Output: [3, 4]

Solution:

To solve this problem using a hash map, we will follow these steps:

Steps to Solve:

1.    Initialize a Hash Map:

o   Use a hash map to store the count of each number in the array.

2.    Count Occurrences:

o   Iterate through the array and update the hash map with the count of each number.

3.    Identify the Repeating and Missing Numbers:

o   Iterate through the numbers from 1 to N and use the hash map to find the repeating number (appears twice) and the missing number (does not appear in the hash map).

Time Complexity: O(N)

Space Complexity: O(N)