Interview coding exercise to parse and build strings based on the number of occurrences of characters.

parseBuild.py

# Take a string as input, such as "a3c4b2", and output a new string of the letters
# repeated the specified number of times i.e. "aaabbcccc"
def parse(string):
    newString = ""
    for i in range(0, len(string)):
        if(string[i].isalpha()):
            currentChar = string[i]
        elif(string[i].isdigit()):
            for j in range(0, int(string[i])):
                newString += currentChar
    return newString

print parse("a3b2c4")

# Take a string as input, such as "aaabbcccc", and output a new string of each letter
# and the number of times it occurred i.e. "a3c4b2"
def build(string):
    newString = ""
    occurrences = {}
    for i in range(0, len(string)):
        if(string[i] not in occurrences):
            occurrences[string[i]] = 1
        else:
            occurrences[string[i]] += 1

    for key in occurrences:
        newString += str(key)
        newString += str(occurrences[key])

    return newString

print build("aaabbcccc")