Question

Formatted question description: https://leetcode.ca/all/344.html

 344	Reverse String

 Write a function that takes a string as input and returns the string reversed.

 Example:
 Given s = "hello", return "olleh".

 @tag-string
 @tag-2pointers

Algorithm

Go from both ends to the middle while swapping characters on both sides.

Code

Java

public class Reverse_String {

    class Solution {
        public void reverseString(char[] s) {

            int l = 0;
            int r = s.length - 1;

            while (l < r) {
                char tmp = s[l];
                s[l] = s[r];
                s[r] = tmp;
                l++;
                r--;
            }
        }
    }

    class Solution_cheat {
        public String reverseString(String input) {

            StringBuilder s = new StringBuilder(input);
            s.reverse();

            return s.toString();
        }
    }
}

// OJ: https://leetcode.com/problems/reverse-string/
// 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--]);
    }
};

class Solution(object):
  def reverseString(self, s):
    """
    :type s: str
    :rtype: str
    """
    return s[::-1]

344 - Reverse String

Question

Algorithm

Code

All Problems

All Solutions