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Problem_04.java
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Problem_04.java
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/**
* LeetCode
* Problem_04.java
*/
package com.deepak.leetcode.Strings;
/**
* <br> Problem Statement :
*
* Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string.
* If there are less than k characters left, reverse all of them. If there are less than 2k but greater than or equal to k characters,
* then reverse the first k characters and left the other as original.
*
* Example:
* Input: s = "abcdefg", k = 2
* Output: "bacdfeg"
*
* Restrictions:
* The string consists of lower English letters only.
* Length of the given string and k will in the range [1, 10000]
*
* </br>
*
* @author Deepak
*/
public class Problem_04 {
/**
* Method to reverse a string for each k occurrences
*
* 0 k 2k 3k
* |-----------|-----------|-----------|---
* +--reverse--+ +--reverse--+
*
* @param s
* @param k
* @return {@link String}
*/
public static String reverseStr(String s, int k) {
if (s == null || s.length() == 0) {
return null;
}
char[] arr = s.toCharArray();
for (int left = 0; left < arr.length; left += 2*k) {
for (int i = left, j = Math.min(left + k - 1, arr.length - 1); i < j; i++, j--) {
char temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
return new String(arr);
}
}