Merge pull request youngyangyang04#785 from Jerry-306/patch-18

添加 100 相同的树、257 二叉树的所有路径  两题的JavaScript版本代码

problems/二叉树中递归带着回溯.md

@@ -439,9 +439,84 @@ func traversal(root *TreeNode,result *[]string,path *[]int){
 }
 ```
 
+JavaScript：
 
+100.相同的树
+```javascript
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} p
+ * @param {TreeNode} q
+ * @return {boolean}
+ */
+var isSameTree = function(p, q) {
+    if (p === null && q === null) {
+        return true;
+    } else if (p === null || q === null) {
+        return false;
+    } else if (p.val !== q.val) {
+        return false;
+    } else {
+        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+    }
+};
+```
+
+257.二叉树的不同路径
 
+> 回溯法：
 
+```javascript
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {string[]}
+ */
+var binaryTreePaths = function(root) {
+    const getPath = (root, path, result) => {
+        path.push(root.val);
+        if (root.left === null && root.right === null) {
+            let n = path.length;
+            let str = '';
+            for (let i=0; i<n-1; i++) {
+                str += path[i] + '->';
+            }
+            str += path[n-1];
+            result.push(str);
+        }
+
+        if (root.left !== null) {
+            getPath(root.left, path, result);
+            path.pop();   // 回溯
+        }
+
+        if (root.right !== null) {
+            getPath(root.right, path, result);
+            path.pop(); 
+        }
+    }
+
+    if (root === null) return [];
+    let result = [];
+    let path = [];
+    getPath(root, path, result);
+    return result;
+};
+```
 
 
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