Reverse String II

• 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.

Link to Git Hub : Code

Example:

Input: s = "abcdefg", k = 2
Output: "bacdfeg"

Restrictions:

1. The string consists of lower English letters only.
2. Length of the given string and k will in the range [1, 10000]

Solution

• Convert the string into a character array
• Find the min (i) and max(j) value for swapping based on k value. 

           int j=Math.min(i+k-1, n-1)

• Swap the elements 

package Algorithms.Strings;
/*
 * Input: s = "abcdefg", k = 2
    Output: "bacdfeg
 */
public class ReverseString2 {
 public static String get(String s,int k)
 {
  //Convert the string in char array
  char [] arr=s.toCharArray();
  //Array length
  int n=arr.length;
  int i=0;
  while(i<n){
   int j=Math.min(i+k-1, n-1);
   //Call the swap function
   swap(arr,i,j);
   //Increment the counter
   i+=2*k;
  }
 //Convert character to string and return
 return String.valueOf(arr); 
 }
 private static void swap(char [] arr, int l, int r)
 {
  while(l<r)
  {
   //Store the first char as temp
   char temp=arr[l];
   //Swap the last element to the first element
   arr[l++]=arr[r];
   //Swap the first element from the temp to last element
   arr[r--]=temp;
  }
 }

}

Iteration