Problem

Write a function that takes an array of integers and returns the sum of the even numbers in the array.
Input: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Output: 30

Solution

// Solution:

function sumEven(arr) {
  let sum = 0;
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] % 2 === 0) {
      sum += arr[i];
    }
  }
  return sum;
}

// Explanation:

// This solution is optimal because it uses a for loop to iterate through the array and check if each element is even. If it is, it adds it to the sum. This solution is optimal because it only iterates through the array once, and it doesn't use any extra space.