equal.py

# source: https://www.hackerrank.com/challenges/equal/problem
# video: https://youtu.be/Mbfs-4URYmg

def equal(arr):
    rounds = float("inf")
    min_val = min(arr)
    # Go through each target value (min, min-1, min-2, ..., min-4)
    for n in range(5): # O(5) = O(1)
        target = min_val - n
        operationCount = 0
        # Go through each value in arr...
        for val in arr: # O(n)
            # calculate difference b/t val and target
            diff = val - target
            # use modular math and add to operationCount
            five_count = diff // 5
            two_count = (diff % 5) // 2
            one_count = (diff % 5) % 2
            operationCount += five_count + two_count + one_count
        rounds = min(rounds, operationCount)
    return rounds # Time Complexity = O(n)