[Algo] 397. Right Shift By N Characters

Right shift a given string by n characters.

Assumptions

• The given string is not null.
• n >= 0.

Examples

• "abc", 4 -> "cab"

public class Solution {
  public String rightShift(String input, int n) {
    // Write your solution here
    if (input.length() == 0) {
      return input;
    }
    char[] charArr = input.toCharArray();
    int len = n % charArr.length;
    // reverse in 3 steps, similar like reverse words in sentense
    reverse(charArr, 0, charArr.length - 1);
    reverse(charArr, 0, len - 1);
    reverse(charArr, len, charArr.length - 1);
    return new String(charArr);
  }

  private void reverse(char[] charArr, int start, int end) {
    while (start < end) {
      char tmp = charArr[start];
      charArr[start] = charArr[end];
      charArr[end] = tmp;
      start += 1;
      end -= 1;
    }
  }
}