Count and Say with Python
The challenge
he count-and-say sequence is the sequence of integers with the first five terms as following:
1 is read off as "one 1" or 11.
11 is read off as "two 1s" or 21.
21 is read off as "one 2, then one 1" or 1211.
Given an integer n where 1 ≤ n ≤ 30, generate the nth term of the count-and-say sequence. You can do so recursively, in other words from the previous member read off the digits, counting the number of digits in groups of the same digit.
Note: Each term of the sequence of integers will be represented as a string.
Example 1:
Example 2:
The solution with Python
def countAndSay(self, n: int) -> str:
# helper function
def countAndSayHelper(s):
# return value
result = []
# loop counter
i = 0
# loop while less than
while i < len(s):
c = 1
# increment counters
while i+1 < len(s) and s[i] == s[i+1]:
i += 1
c += 1
# add string to the return list
result.append(str(c)+s[i])
# increment
i += 1
# return a string from the created list
return ''.join(result)
# set default return string value
s = "1"
# loop through input size
for i in range(n-1):
# use helper function
s = countAndSayHelper(s)
# return answer
return s