find_most_common_number_in_list.py

# conversation from twitter: https://twitter.com/driscollis/status/1475571532898385927

# This function's worst case performance is n*log(n)
def find_most_common_number_in_list(number_list):
    # O(n*log(n)))
    counts = {}
    for number in number_list:
        try:
            counts[number] += 1
        except:
            counts[number] = 1
    
    # O(n)
    sortable_list = [[item[1], item[0]] for item in counts.items()]

    # O(n*log(n))
    sortable_list.sort(reverse=True)

    # O(1)
    return sortable_list[0][1]