题目
Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them. If there are less than 2k but greater than or equal to k characters, then reverse the first k characters and left the other as original.
Example:
Input: s = "abcdefg", k = 2
Output: "bacdfeg"
Restrictions:
- The string consists of lower English letters only.
- Length of the given string and k will in the range [1, 10000]
难度
Easy
方法
每次处理s[0:2k]，将s[0:k]逆序后拼接s[k:2k]，然后将s[2k:]赋值给s，循环处理直至s为空即可
python代码
class Solution(object):
def reverseStr(self, s, k):
"""
:type s: str
:type k: int
:rtype: str
"""
result = ""
while s:
temp = s[0:k]
result += temp[::-1] + s[k:2*k]
s = s[2*k:]
return result
assert Solution().reverseStr("abcdefg", 2) == "bacdfeg"
