541.reverse-string-ii.java

/*
 * @lc app=leetcode id=541 lang=java
 *
 * [541] Reverse String II
 */

// @lc code=start
class Solution {
    public String reverseStr(String s, int k) {
        char[] arr = s.toCharArray();
        for (int i = 0; i < arr.length; i += 2 * k) {
            int start = i;
            int end = Math.min(i + k - 1, arr.length - 1);
            
            while (start < end) {
                char temp = arr[start];
                arr[start++] = arr[end];
                arr[end--] = temp;
            }
        }
        
        return new String(arr);
    }
}
// @lc code=end