Write a function that reverses a string. The input string is given as an array of characters char[].
Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
You may assume all the characters consist of printable ascii characters.
Example 1:
Input: ["h","e","l","l","o"]
Output: ["o","l","l","e","h"]Example 2:
Input: ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]题目要求我们反转一个字符串。
这一题的解题思路是用 2 个指针，指针对撞的思路，来不断交换首尾元素，即可。