class Solution(object):
    def reverseString(self, s):
        """
        :type s: str
        :rtype: str
        """
        s = list(s)
        left = 0
        right = len(s) - 1
        while left < right:
            s[left], s[right] = s[right], s[left]
            left += 1
            right -= 1
        return ''.join(s)
class Solution(object):
    def reverseString(self, s):
        """
        :type s: str
        :rtype: str
        """
        s = list(s)
        left = 0
        right = len(s) - 1
        while left < right:
            s[left], s[right] = s[right], s[left]
            left += 1
            right -= 1
        return ''.join(s)
:type s: str         :rtype: str