feat: add typescript solution to lc problem: No.0617.Merge Two Binary Trees (doocs#486)

Author: zhaocchen

solution/0600-0699/0617.Merge Two Binary Trees/README.md

@@ -97,6 +97,33 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+ function mergeTrees(root1: TreeNode | null, root2: TreeNode | null): TreeNode | null {
+    if (root1 == null && root2 == null) return null;
+    if (root1 == null) return root2;
+    if (root2 == null) return root1;
+    let left = mergeTrees(root1.left, root2.left);
+    let right = mergeTrees(root1.right, root2.right);
+    return new TreeNode(root1.val + root2.val, left, right);
+}; 
+```
+
 ### **C++**
 
 ```cpp

solution/0600-0699/0617.Merge Two Binary Trees/README_EN.md

@@ -95,6 +95,33 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+ function mergeTrees(root1: TreeNode | null, root2: TreeNode | null): TreeNode | null {
+    if (root1 == null && root2 == null) return null;
+    if (root1 == null) return root2;
+    if (root2 == null) return root1;
+    let left = mergeTrees(root1.left, root2.left);
+    let right = mergeTrees(root1.right, root2.right);
+    return new TreeNode(root1.val + root2.val, left, right);
+}; 
+```
+
 ### **C++**
 
 ```cpp

solution/0600-0699/0617.Merge Two Binary Trees/Solution.ts

@@ -0,0 +1,22 @@
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+ function mergeTrees(root1: TreeNode | null, root2: TreeNode | null): TreeNode | null {
+    if (root1 == null && root2 == null) return null;
+    if (root1 == null) return root2;
+    if (root2 == null) return root1;
+    let left = mergeTrees(root1.left, root2.left);
+    let right = mergeTrees(root1.right, root2.right);
+    return new TreeNode(root1.val + root2.val, left, right);
+};