BinarySearchIO - 24-hour time

'''
Given a string s, representing a 12-hour clock time with am/pm, return its 24-hour equivalent.
Example 1
Input
s = "05:30pm"
Output
"17:30"
'''

def solve(s):
    length = len(s)
    changeFlag = False
    if s[length-2] == 'p' and s[length-1] == 'm':
        changeFlag = True
    # changeFlag = False <----> "am"
    if changeFlag == False:
        if s[0:2] != "12":
            return s[0:5]
        else:
            return "00" + s[2:5]
    # changeFlag = True <----> "pm"
    else:
        time = int(s[0:2])
        newTime = time + 12
        if newTime != 24:
            return str(newTime) + s[2:5]
        elif newTime == 24:
            return s[0:5]

# MAIN FUNCTION
print(solve("05:30pm"))
print(solve("05:30am"))
print(solve("12:00pm"))
print(solve("12:00am"))