[leetcode] Count and Say @ Python
The count-and-say sequence is the sequence of integers beginning as follows:
1, 11, 21, 1211, 111221, ...
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, generate the nth sequence.
Note: The sequence of integers will be represented as a string.
Code:
復制代碼
class Solution:
# @return a string
def countAndSay(self, n):
#思路：遍歷，每次對前面的string進行分析，輸出
s= '1'
for i in range(n-1):
prev = newS =''
num = 0
for curr in s:
if prev !='' and prev != curr:
newS += str(num) + prev # how many times the value "prev" appears
num = 1
else:
num += 1
prev = curr
newS += str(num) + prev
s = newS
return s
