Reverse String

Posted by Bill on March 11, 2023

Reverse String

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.

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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"]

Java Solution

Solution:

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class Solution {
    public void reverseString(char[] s) {
		int head = 0;
		int tail = s.length - 1;
		while(head < tail){
			char tmp = s[head];
			s[head] = s[tail];
			s[tail] = tmp;
			head++;
			tail--;
		}
	}
}