LeetCode： Reverse String

Question

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"]

Solution#1

def reverse_string(s)
  s.reverse!
end

Solution#2

def reverse_string(s)
  i = 0
  while i < s.length/2
     s[i], s[s.length-i-1] =  s[s.length-i-1], s[i]
     i+=1
  end
  s
end