添加（0617.合并二叉树.md）：增加typescript版本

problems/0617.合并二叉树.md

@@ -583,6 +583,56 @@ var mergeTrees = function(root1, root2) {
 
 ```
 
+## TypeScript
+
+> 递归法：
+
+```type
+function mergeTrees(root1: TreeNode | null, root2: TreeNode | null): TreeNode | null {
+    if (root1 === null) return root2;
+    if (root2 === null) return root1;
+    const resNode: TreeNode = new TreeNode(root1.val + root2.val);
+    resNode.left = mergeTrees(root1.left, root2.left);
+    resNode.right = mergeTrees(root1.right, root2.right);
+    return resNode;
+};
+```
+
+> 迭代法：
+
+```typescript
+function mergeTrees(root1: TreeNode | null, root2: TreeNode | null): TreeNode | null {
+    if (root1 === null) return root2;
+    if (root2 === null) return root1;
+    const helperQueue1: TreeNode[] = [],
+        helperQueue2: TreeNode[] = [];
+    helperQueue1.push(root1);
+    helperQueue2.push(root2);
+    let tempNode1: TreeNode,
+        tempNode2: TreeNode;
+    while (helperQueue1.length > 0) {
+        tempNode1 = helperQueue1.shift()!;
+        tempNode2 = helperQueue2.shift()!;
+        tempNode1.val += tempNode2.val;
+        if (tempNode1.left !== null && tempNode2.left !== null) {
+            helperQueue1.push(tempNode1.left);
+            helperQueue2.push(tempNode2.left);
+        } else if (tempNode1.left === null) {
+            tempNode1.left = tempNode2.left;
+        }
+        if (tempNode1.right !== null && tempNode2.right !== null) {
+            helperQueue1.push(tempNode1.right);
+            helperQueue2.push(tempNode2.right);
+        } else if (tempNode1.right === null) {
+            tempNode1.right = tempNode2.right;
+        }
+    }
+    return root1;
+};
+```
+
+
+
 
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