【刷算法】LeetCode.2-两数相加

示例：
输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)
输出：7 -> 0 -> 8
原因：342 + 465 = 807
复制代码

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */
var addTwoNumbers = function(l1, l2) {
  if(l1 === null) return l2;
  if(l2 === null) return l1;
  let cur1 = l1, cur2 = l2;
  let isCarried =  false;
  let cur = null, head = null;
  while(cur1 !== null && cur2 !== null) {
    let sum = cur1.val +  cur2.val;
    sum = isCarried ? sum+1 : sum;
    isCarried = false;
    if(sum >= 10) {
      sum  = sum % 10;
      isCarried = true;
    }
    let node = new ListNode(sum);
    if(head === null) {
      head = node;
    }
    if(cur === null) {
      cur = node;
    } else {
      cur.next = node;
      cur = node;
    }
    cur1 = cur1.next;
    cur2 = cur2.next;
  }
  let lastCur = cur1 === null ? cur2 : cur1;
  while(lastCur !== null) {
    let sum = isCarried ? lastCur.val+1 : lastCur.val;
    isCarried = false;
    if(sum >= 10) {
      sum = sum % 10;
      isCarried = true;
    }
    cur.next = new ListNode(sum);
    cur = cur.next;
    lastCur = lastCur.next;
  }
  if(isCarried) {
    cur.next = new ListNode(1)
  }
  return head;
};