Thread: CodingBat code efficency question

https://codingbat.com/prob/p191914

Doing this CodingBat problem, and I just was wondering about the solution I came up with compared to theirs. Obviously neither is "wrong" but I was just wondering (in the long run) which is the better syntax / more efficient code?

Their Solution

    public String notString(String str) {
  if (str.length() >= 3 && str.substring(0, 3).equals("not")) {
    return str;
  }
 
  return "not " + str;
}
 
And my solution
 
public String notString(String str) {
  if(str.indexOf("not") == 0){
    return str;
  }
  return "not " + str;
}

And my solution

public String notString(String str) {
  if(str.indexOf("not") == 0){
    return str;
  }
  return "not " + str;
}