【ruby】leetcode 练习 ：Reverse String

Example 1:

Input: s = ["h","e","l","l","o"]
Output: ["o","l","l","e","h"]

Example 2:

Input: s = ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]

解法：
这题可以很简单的使用 reverse! 解决， 但是这边挑战不使用 reverse 该如何解

第一种方法，建立额外空间纪录

缺点是会佔用到比较多额外空间

def reverse_string(s)  len = s.length   arr = []  while len > 0    arr << s.pop    len -= 1  end  arrend

第二种方法 直接交换左右两边的值

若是阵列长度为奇数，两边阵列位置相等表示已交换完成，若阵列长度是偶数，左右数值不会相遇在同一位址，因此当左边阵列位址将大于右边阵列位址表示交换完毕。

def reverse_string(s)    left = 0    right = s.length - 1    while left < right        t = s[left]        s[left] = s[right]        s[right] = t        left += 1        right -= 1    end    send