Question

Codingbat.com array question

This is a simple array question, not for homework, just for general knowledge before I take another programming class next fall.

Given an array of ints, return true if 6 appears as either the first or last element in the array. The array will be length 1 or more.

firstLast6({1, 2, 6}) → true
firstLast6({6, 1, 2, 3}) → true
firstLast6({3, 2, 1}) → false

The problem I have is that you are not supposed to use any loops to traverse the array. How can this be written to avoid an index out of bounds exception if I don’t know the total number of ints in the input data?

My solution — it works but not exactly the answer they were looking for.

public boolean firstLast6(int[] nums) {
  for (int i=0; i < (nums.length ); i++)
  {

  if (i == 0 && nums[i] == 6)
  { 
  return true;
  }

  else if (i == (nums.length - 1) && nums[i] ==6)
  {

  return true;
  }
  }
  return false;
}

Answer 1

You would use the length property to access the last index:

public boolean firstLast6(int[] nums) {
    if (nums == null || nums.length == 0) {
        return false;
    }

    return nums[0] == 6 || nums[nums.length - 1] == 6;
}

EDIT: added check for null or empty array.