"""

Given a string with a certain rule: k[string] should be expanded to string k times. So for example, 3[abc] should be expanded to abcabcabc. Nested expansions can happen, so 2[a2[b]c] should be expanded to abbcabbc.

Your starting point:

def decodeString(s):

# Fill this in.

print decodeString('2[a2[b]c]')

# abbcabbc

"""

def decodeString(s):

result = ""

stack = []

i = 0

while i < len(s):

if s[i] == "]":

temp = ""

while stack and stack[-1] != "[":

temp = stack.pop() + temp

stack.pop() # remote [

count = ""

while stack and stack[-1].isdigit():

count = stack.pop() + count

stack.append(int(count)*temp)

else:

stack.append(s[i])

i += 1

return "".join(stack)

print decodeString('2[a2[b]c]')