Java > Array-2 > sum13 (CodingBat Solution)

Problem:

Return the sum of the numbers in the array, returning 0 for an empty array. Except the number 13 is very unlucky, so it does not count and numbers that come immediately after a 13 also do not count.

sum13({1, 2, 2, 1}) → 6
sum13({1, 1}) → 2
sum13({1, 2, 2, 1, 13}) → 6

Solution:

public int sum13(int[] nums) {
  int sum = 0;
  
  for (int i = 0; i < nums.length; i++) {
    if(nums[i] != 13) {
      sum += nums[i];
      if(i>0 && nums[i-1] == 13)
        sum -= nums[i];
    }
  }
  return sum;
}