CheckIO - Home Challenge 4 : The Most Wanted Letter

checkio.1.04.TheMostWantedLetter.py

# CheckIO - Home Challenge 4 : The Most Wanted Letter
# http://checkio.org

# You are given a text, which contains different english letters and punctuation symbols. 
# You should find the most frequent letter in the text. The letter returned must be in lower case.
# While checking for the most wanted letter, casing does not matter, 
# so for the purpose of your search, "A" == "a". 
# Make sure you do not count punctuation symbols, digits and whitespaces, only letters.
# If you have two or more letters with the same frequency, then return the letter which comes first in the latin alphabet.
# For example -- "one" contains "o", "n", "e" only once for each, thus we choose "e".
# Input: A text for analysis as a string (unicode for py2.7).
# Output: The most frequent letter in lower case as a string.
# Precondition: The password contains only ASCII symbols. 0 < len(text) ≤ 105

def checkio(text):

    charList='abcdefghijklmnopqrstuvwxyz' # Chars to find
    text=text.lower()                     # Setting text to low chars
    
    # Looping chars
    i=0         # index
    total=0     # Total chars found
    mainChar='' # Char most repeated
    while i<len(charList) and total<len(text):
        char=charList[i]
        i+=1
        counts=text.count(char)
        total+=counts
        if (mainChar == '' or counts > maxRepeats):
            mainChar=char
            maxRepeats=counts

    return mainChar

if __name__ == '__main__':
    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert checkio("Hello World!") == "l", "Hello test"
    assert checkio("How do you do?") == "o", "O is most wanted"
    assert checkio("One") == "e", "All letter only once."
    assert checkio("Oops!") == "o", "Don't forget about lower case."
    assert checkio("AAaooo!!!!") == "a", "Only letters."
    assert checkio("abe") == "a", "The First."
    print("Start the long test")
    assert checkio("a" * 9000 + "b" * 1000) == "a", "Long."
    print("The local tests are done.")