# Count Largest Group

### Lessons Learned: HashMaps

## Question: Given an integer `n`

. Each number from `1`

to `n`

is grouped according to the sum of its digits.

## Return how many groups have the largest size.

Example:

N = 13

Output: 4

Explanation: We arrive at 9 groups in total: [1, 10], [2,11], [3,12], [4,13], [5], [6], [7], [8], [9]. There are 4 groups with largest size.

## Solution

## Approach 1: HashMap

Our solution will take on the following steps:

Calculate the sum of digits if the number is multidigit

Keep a count of the key and the value (key = sum of digits, value = number)

Keep a track of the max frequency count for the key

Retrieve a list of all the values from the map and count the values which are the same as the max size.