Array String Hash Map Sliding Window
Intermediate Level

Implement the fruitIntoBasketsMaxCount method that returns the maximum fruits collected using at most two fruit types.

The input contains an array fruits and its length size. Each value represents a type of fruit on a tree in a row.

You have two baskets, and each basket can contain only one fruit type. Your task is to return the maximum number of fruits you can collect from a continuous section of trees.

This means you need the longest continuous subarray that contains at most two distinct fruit types.

Example 1
Input:
fruits (int[]) = [1,2,1]
size (int) = 3
Return:
(int) 3
Example 2
Input:
fruits (int[]) = [0,1,2,2]
size (int) = 4
Return:
(int) 3
Example 3
Input:
fruits (int[]) = [1,2,3,2,2]
size (int) = 5
Return:
(int) 4

Use a sliding window with a frequency map of fruit types.

Expand the window to include more trees. If the window contains more than two fruit types, move the left pointer forward and update counts until only two types remain.

For every valid window, update the maximum length because that length is the number of fruits collected.

Pseudocode:

function fruitIntoBasketsMaxCount(fruits, size):
    left = 0
    best = 0
    frequency = empty map
    for right from 0 to size - 1:
        add fruits[right] to frequency
        while number of keys in frequency > 2:
            decrease frequency of fruits[left]
            if frequency of fruits[left] becomes 0:
                remove fruits[left] from frequency
            left++
        best = maximum(best, right - left + 1)
    return best
Run your code to see the result.