Problem

Given an array of integers, write a function that finds the sum of all the elements in the array.
Input: [1, 2, 3, 4]
Output: 10

Solution

// Solution:

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

// This solution is optimal because it uses a for loop to iterate through the array and add each element to the sum variable.
// This solution is O(n) because the time it takes to run is directly proportional to the size of the input.