Array Max Min Snakes And Ladders Java

Question

I am making a snakes and ladders game on console. I'm trying to make it so that the ladderBottoms is always less than the ladderTops. However I keep running into errors. The code I have been trying is a recursive method for it to redo the method until it is correct...

public static void ladders() {
  for (int i = 0 ; i < 6 ; i++){
   ladderBottoms [i] = (int) ((Math.random () * 80)+1);
   ladderTops [i] = (int) ((Math.random () * 80)+1);`
      if(ladderBottom[i] > ladderTop[i])
       ladders();
  }//for
}//ladders

Answer 1

This code is not good. You are attempting, on each recursion to regenerate the entire array from scratch! In fact the probability of your successfully generating the ladders is about 1 / 64.

If I were you, I'd drop the recursion and adjust the loop:

public static void ladders() {
  for (int i = 0 ; i < 6 ; ){    
   ladderBottoms [i] = (int) ((Math.random () * 80)+1);
   ladderTops [i] = (int) ((Math.random () * 80)+1);
      if(ladderBottom[i] <= /*do you really want =*/ ladderTop[i]){
           i++; /* this is OK so increment; else have another go*/
      }
  }//for
}//ladders

An empty expression in a for loop is perfectly legal in Java.

Do take note of my comment in the code. Do you really want a unit-length ladder? If not then replace the <= in the conditional with <.

As a rule of thumb, always try to avoid recursive functions: they can be difficult to follow in a 3am debugging session and also, particularly with ramdomisation, can, once in a while, cause a stack to overflow.

Answer 2

Don't recursive the total method just retry randoms another time.

public static void ladders()
{
    for (int i = 0 ; i < 6 ; i++)
    {
        do{
            ladderBottoms [i] = (int) ((Math.random () * 80)+1);
            ladderTops [i] = (int) ((Math.random () * 80)+1);
        }while(ladderBottom[i] >= ladderTop[i]);
    }//for
}//ladders

Not tested.