Java > Recursion-1 > changeXY (CodingBat Solution)

Problem:

Given a string, compute recursively (no loops) a new string where all the lowercase 'x' chars have been changed to 'y' chars.

changeXY("codex") → "codey"
changeXY("xxhixx") → "yyhiyy"
changeXY("xhixhix") → "yhiyhiy"


Solution:

public String changeXY(String str) {
  if (str.equals("")) return str;
  if (str.charAt(0) == 'x') return "y" + changeXY(str.substring(1));
  return str.charAt(0) + changeXY(str.substring(1));
}

4 comments:

  1. ioannisaDecember 10, 2019 at 2:36 AM

    public String changeXY(String str) {
    int idx = str.indexOf("x");

    if (idx==-1)
    return str;

    if (idx==0)
    return changeXY("y"+str.substring(1));
    else if (idx==str.length()-1)
    return changeXY(str.substring(0, str.length()-1)+"y");
    else{
    return changeXY(str.substring(0, idx)+"y"+str.substring(idx+1, str.length()));
    }

    }

    ReplyDelete
  2. ioannisaDecember 10, 2019 at 2:40 AM

    public String changePi(String str) {
    int idx = str.indexOf("pi");
    if (idx==-1)
    return str;

    return changePi(str.substring(0,idx)+"3.14"+str.substring(idx+2));
    }

    ReplyDelete
  3. ZeroJuly 8, 2020 at 5:49 AM

    public String changeXY(String str) {
    return str.replace('x','y');
    }

    ReplyDelete
  4. omerorhanJanuary 24, 2021 at 10:45 PM

    public boolean array6(int[] nums, int index) {
    if (nums.length == 0 || index == nums.length)
    return false;
    return nums[index] == 6 || array6(nums, index + 1);
    }

    ReplyDelete