Partition array into three parts with equal sum

We will calculate the sum of the array. If the sum is not divisible by 3, we return False. Otherwise, we will iterate over the array and check if the sum of the current subarray is equal to the sum of the array divided by 3. If it is, we increment the count. If the count is 3, we return True.

class Solution:
    def canThreePartsEqualSum(self, arr: List[int]) -> bool:
        if sum(arr) % 3 != 0:
            return False

        average = sum(arr) // 3
        part, count = 0, 0
        for num in arr:
            part += num
            if part == average:
                count += 1
                part = 0

        return count >= 3

Time complexity: O(n)
Space complexity: O(1)