structy-020-sumList.js

// https://structy.net/problems/sum-list

class Node {
  constructor(val) {
    this.val = val;
    this.next = null;
  }
}

// p: head of ll (num)
// r: num

// recursion:
const sumList = (head) => {
  if (!head) return 0;

  return head.val + sumList(head.next);
};

const a = new Node(2);
const b = new Node(8);
const c = new Node(3);
const d = new Node(-1);
const e = new Node(7);

a.next = b;
b.next = c;
c.next = d;
d.next = e;

// 2 -> 8 -> 3 -> -1 -> 7

console.log(sumList(a)); // 19

// // iteration:
// const sumList = (head) => {
//     let sum = 0;
//     let current = head;

//     while (current) {
//       sum += current.val;
//       current = current.next;
//     }

//     return sum;
//   };