lc 002

Author: dryyun

LeetCode/ProblemSet/002.Add Two Numbers/README.md

@@ -1,11 +1,9 @@
 # 两数相加
 
 ## 链接
-
 https://leetcode-cn.com/problems/add-two-numbers/description/
 
 ## 描述
-
 给定两个非空链表来表示两个非负整数。位数按照逆序方式存储，它们的每个节点只存储单个数字。将两数相加返回一个新的链表。  
 
 你可以假设除了数字 0 之外，这两个数字都不会以零开头。  
@@ -17,3 +15,7 @@ https://leetcode-cn.com/problems/add-two-numbers/description/
 原因：342 + 465 = 807
 ```
 
+## 思路
+就是两数相加，注意进位
+
+可以复用 l1，只修改 val，而不是完全重新 new

LeetCode/ProblemSet/002.Add Two Numbers/add-two-numbers.js

@@ -7,28 +7,24 @@
 const {LeetCode, ListNode} = require('../../leetcode.js');
 
 var addTwoNumbers = function (l1, l2) {
-    let list = null;
-    let node = null;
-    let val = null;
-    let carry = 0;
+    let head = l1, node = null;
+    let cur = 0, carry = 0;
     while (l1 || l2) {
         let l1v = l1 ? l1.val : 0;
         let l2v = l2 ? l2.val : 0;
 
-        let sum = l1v + l2v + carry;
-        if (sum >= 10) {
+        cur = l1v + l2v + carry;
+        carry = 0;
+        if (cur >= 10) {
             carry = 1;
-            val = sum - 10;
-        } else {
-            carry = 0;
-            val = sum;
+            cur -= 10;
         }
 
-        if (!list && !node) {
-            node = new ListNode(val);
-            list = node;
+        if (l1) {
+            l1.val = cur;
+            node = l1;
         } else {
-            node.next = new ListNode(val);
+            node.next = new ListNode(cur);
             node = node.next;
         }
 
@@ -40,13 +36,23 @@ var addTwoNumbers = function (l1, l2) {
         node.next = new ListNode(carry);
     }
 
-    return list;
+    return head;
 };
 
 let l1 = LeetCode.arrToList([2, 4, 3]);
 let l2 = LeetCode.arrToList([5, 6, 4]);
 
-let list = addTwoNumbers(l1, l2);
+let list = addTwoNumbers(l1, l2); // 342 + 465 = 807
+LeetCode.showList(list);
+
+l1 = LeetCode.arrToList([5]);
+l2 = LeetCode.arrToList([5]);
+
+list = addTwoNumbers(l1, l2); // 5 + 5 = 10
 LeetCode.showList(list);
 
+l1 = LeetCode.arrToList([2, 4, 6]);
+l2 = LeetCode.arrToList([5, 6, 4]);
 
+list = addTwoNumbers(l1, l2); // 642 + 465 = 1107
+LeetCode.showList(list);

LeetCode/README.md

@@ -19,6 +19,7 @@ _**刷题真心累，真心花时间，主要还是智商不够**_
 - 2018.9.21 复习总结之前的刷题，不能一味刷题，而不总结归纳。  
 
 
-| # | 题目 | 打败 | 难度 |
-|:---:|:---:|:---:|:---:|
-| 001 | [两数之和](./ProblemSet/001.Two%20Sum) | 95% | 简单 |
+| # | 题目 | 执行用时 |打败 | 难度 |
+|:---:|:---:|:---:|:---:|:---:|
+| 001 | [两数之和](./ProblemSet/001.Two%20Sum)| 70 ms | 95% | 简单 |
+| 002 | [两数相加](./ProblemSet/002.Add%20Two%20Numbers) | 180 ms | 65 % | 中等 | 

notes/binary-tree-traversal.js

@@ -1,7 +1,7 @@
 /**
  * 二叉树遍历的实现
  */
-const {LeetCode, TreeNode} = require('../leetcode.js');
+const {LeetCode, TreeNode} = require('../LeetCode/leetcode.js');
 
 class BinaryTreeTraversal {
     /**