344

344. Reverse String (Easy)

Write a function that reverses a string. The input string is given as an array of characters s.

You must do this by modifying the input array in-place with O(1) extra memory.

 

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"]

 

Constraints:

• 1 <= s.length <= 105
• s[i] is a printable ascii character.

Companies:
Microsoft, Amazon, Facebook, Apple, Oracle, tcs

Related Topics:
Two Pointers, String, Recursion

Similar Questions:

• Reverse Vowels of a String (Easy)
• Reverse String II (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/reverse-string/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    void reverseString(vector<char>& s) {
        int i = 0, j = s.size() - 1;
        while (i < j) swap(s[i++], s[j--]);
    }
};