题目:
反转字符串: 编写一个函数,其作用是将输入的字符串反转过来。输入字符串以字符数组 char[] 的形式给出。 不要给另外的数组分配额外的空间,你必须原地修改输入数组、使用 O(1) 的额外空间解决这一问题。 你可以假设数组中的所有字符都是 ASCII 码表中的可打印字符。
示例 1:
输入:["h","e","l","l","o"]
输出:["o","l","l","e","h"]
示例 2:
输入:["H","a","n","n","a","h"]
输出:["h","a","n","n","a","H"]
思路:
双指针。
程序:
class Solution: def reverseString(self, s: List[str]) -> None: """ Do not return anything, modify s in-place instead. """ if not s: return s if len(s) == 1: return s index1 = 0 index2 = len(s) - 1 while index1 <= index2: s[index1], s[index2] = s[index2], s[index1] index1 += 1 index2 -= 1 return s