raivatshah

// 1A
function compute_e(lst) {
    function helper_acc(xs, n, current){
        if(is_empty_list(xs)) {
            return current;
        } else {
            if (n % 2 === 0){
                return helper_acc(tail(xs), n + 1, current + head(xs)); //if index is even (so number is at odd i), just add it to the sum
            } else {
                return helper_acc(tail(xs), n + 1, current + head(xs) * 3); //if index is odd (so number is at even i), multiply by 3 and then add to sum 

raivatshah

//Obtain sum of array using for-loops

/* Thought process: this is the same as our sum for lists but in an imperative style of programming. So the idea is the same as recursion

Array indexes start at 0 and end at n - 1, where n is the number of elements in the array. Therefore, we start at 0 and end at n-1, where we move 1 element each time 
*/

function sumArray(arr) {
  let sum = 0; //initialize counter at 0 because we haven't added anything yet (we usually start counting with 0 in CS).