Question Link:

https://leetcode.com/problems/reverse-string/

Question Description

Reverse String in place
Input: s = [“h”,”e”,”l”,”l”,”o”]
Output: [“o”,”l”,”l”,”e”,”h”]

Simulation

Solution 1: Use two pointers to swap values.

Iteration 1: [“h”,”e”,”l”,”l”,”o”] -> [“o”,”e”,”l”,”l”,”h”]
Iteration 2: [“o”,”e”,”l”,”l”,”h”] -> [“o”,”I”,”l”,”e”,”h”]
Iteration 3: [“o”,”I”,”l”,”e”,”h”] -> [“o”,”I”,”l”,”e”,”h”]

Implementation

public void reverseString(char[] s) {
  int left = 0, right = s.length - 1;
  char temp;
  while (left <= right) {
    temp = s[left];
    s[left] = s[right];
    s[right] = temp;
    right--;
    left++;
  }
}