ex1.py

string = "aaaaa"
substring = "aa"

total = 0

i = 0
j = 0

oldIndex = 0
# len(string) -> string.length
while i < len(string):
    # string[i] -> string.charAt(i)
    if string[i] == substring[j]:
        if j == 0:
            oldIndex = i

        if j == len(substring) - 1:
            total = total + 1
            j = 0
            i = oldIndex
        else:
            j = j + 1
    elif j != 0:
        i = oldIndex
        j = 0

    i = i + 1

print total