Help me: Time limit exceed

Question

Given 2 integers a and b. Find the last 2 digits of the number a^b
Example:
a = 3 and b = 6 --> lastTwoDigits(a, b) = "29"
a = 7 and b = 4 --> lastTwoDigits(a, b) = "01"

def lastTwoDigits(a,b):
n=a
b=b-1
a=str(a)
if len(a)<2:
a="0"+a
elif len(a)>2:
a=a[len(a)-2]+a[len(a)-1]
else: a = a
while b>0:
b=b-1
a= "0"+str(int(a)*n)
a=a[len(a)-2]+a[len(a)-1]
return a

Answer 1

My algorithm is correct. But Time limit exceed, so Fail

Answer 2

Thank you so much :)