feat: azl397985856#129

Author: luzhipeng

README.en.md

@@ -104,6 +104,7 @@ The data structures mainly includes:
 - [0121.best-time-to-buy-and-sell-stock](./problems/121.best-time-to-buy-and-sell-stock.md)
 - [0122.best-time-to-buy-and-sell-stock-ii](./problems/122.best-time-to-buy-and-sell-stock-ii.md)
 - [0125.valid-palindrome](./problems/125.valid-palindrome.md) 🆕
+- [0129.sum-root-to-leaf-numbers](./problems/129.sum-root-to-leaf-numbers.md) 🆕
 - [0136.single-number](./problems/136.single-number.md)
 - [0155.min-stack](./problems/155.min-stack.md) 🆕
 - [0167.two-sum-ii-input-array-is-sorted](./problems/167.two-sum-ii-input-array-is-sorted.md)

README.md

@@ -101,6 +101,7 @@ leetcode 题解，记录自己的 leetcode 解题之路。
 - [0121.best-time-to-buy-and-sell-stock](./problems/121.best-time-to-buy-and-sell-stock.md)
 - [0122.best-time-to-buy-and-sell-stock-ii](./problems/122.best-time-to-buy-and-sell-stock-ii.md)
 - [0125.valid-palindrome](./problems/125.valid-palindrome.md) 🆕
+- [0129.sum-root-to-leaf-numbers](./problems/129.sum-root-to-leaf-numbers.md) 🆕
 - [0136.single-number](./problems/136.single-number.md)
 - [0155.min-stack](./problems/155.min-stack.md) 🆕
 - [0167.two-sum-ii-input-array-is-sorted](./problems/167.two-sum-ii-input-array-is-sorted.md)

assets/drawio/129.sum-root-to-leaf-numbers.drawio

@@ -0,0 +1 @@
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assets/problems/129.sum-root-to-leaf-numbers-1.jpg

@@ -0,0 +1,106 @@
+## 题目地址
+
+https://leetcode.com/problems/sum-root-to-leaf-numbers/description/
+
+## 题目描述
+
+```
+Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.
+
+An example is the root-to-leaf path 1->2->3 which represents the number 123.
+
+Find the total sum of all root-to-leaf numbers.
+
+Note: A leaf is a node with no children.
+
+Example:
+
+Input: [1,2,3]
+    1
+   / \
+  2   3
+Output: 25
+Explanation:
+The root-to-leaf path 1->2 represents the number 12.
+The root-to-leaf path 1->3 represents the number 13.
+Therefore, sum = 12 + 13 = 25.
+Example 2:
+
+Input: [4,9,0,5,1]
+    4
+   / \
+  9   0
+ / \
+5   1
+Output: 1026
+Explanation:
+The root-to-leaf path 4->9->5 represents the number 495.
+The root-to-leaf path 4->9->1 represents the number 491.
+The root-to-leaf path 4->0 represents the number 40.
+Therefore, sum = 495 + 491 + 40 = 1026.
+
+```
+
+## 思路
+
+这是一道非常适合训练递归的题目。虽然题目不难，但是要想一次写正确，并且代码要足够优雅却不是很容易。
+
+这里我们的思路是定一个递归的helper函数，用来帮助我们完成递归操作。
+递归函数的功能是将它的左右子树相加，注意这里不包括这个节点本身，否则会多加，
+我们其实关注的就是叶子节点的值，然后通过层层回溯到root，返回即可。
+
+整个过程如图所示：
+
+![129.sum-root-to-leaf-numbers-1](../assets/problems/129.sum-root-to-leaf-numbers-1.jpg)
+
+
+那么数字具体的计算逻辑，如图所示，相信大家通过这个不难发现规律：
+
+![129.sum-root-to-leaf-numbers-2](../assets/problems/129.sum-root-to-leaf-numbers-2.jpg)
+
+## 关键点解析
+
+- 递归分析
+
+## 代码
+
+```js
+/*
+ * @lc app=leetcode id=129 lang=javascript
+ *
+ * [129] Sum Root to Leaf Numbers
+ */
+function helper(node, cur) {
+  if (node === null) return 0;
+  const next = node.val + cur * 10;
+
+  if (node.left === null && node.right === null) return next;
+
+  const l = helper(node.left, next);
+  const r = helper(node.right, next);
+
+  return l + r;
+}
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+var sumNumbers = function(root) {
+  // tag: `tree` `dfs` `math`
+  return helper(root, 0);
+};
+```
+
+## 相关题目
+
+- [sum-of-root-to-leaf-binary-numbers](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers/)
+
+> 这道题和本题太像了，跟一道题没啥区别
+