Update Swift/617. Merge Two Binary Trees.swift

Author: liuchuo

Swift/617. Merge Two Binary Trees.swift

@@ -0,0 +1,21 @@
+// 617. Merge Two Binary Trees
+// 100 ms
+func mergeTrees(_ t1: TreeNode?, _ t2: TreeNode?) -> TreeNode? {
+    let root = mergeNote(t1, t2)
+    root?.left = mergeTrees(t1?.left, t2?.left)
+    root?.right = mergeTrees(t1?.right, t2?.right)
+
+    return root
+}
+
+func mergeNote(_ t1: TreeNode?, _ t2: TreeNode?) -> TreeNode? {
+    if let c1 = t1, let c2 = t2 {
+        return TreeNode(c1.val + c2.val)
+    } else if let c1 = t1 {
+        return TreeNode(c1.val)
+    } else if let c2 = t2 {
+        return TreeNode(c2.val)
+    } else {
+        return nil
+    }
+}