Update Swift/543. Diameter of Binary Tree.swift

Author: liuchuo

Swift/543. Diameter of Binary Tree.swift

@@ -0,0 +1,20 @@
+// 543. Diameter of Binary Tree
+// 32 ms
+private var diameter = 0
+private func diameterOfNode(_ root: TreeNode?) -> Int {
+    var lv = 0, rv = 0
+
+    if let l = root?.left {
+        lv = 1 + diameterOfNode(l)
+    }
+    if let r = root?.right {
+        rv = 1 + diameterOfNode(r)
+    }
+    diameter = max(diameter, lv + rv)
+    return max(lv, rv)
+}
+
+func diameterOfBinaryTree(_ root: TreeNode?) -> Int {
+    diameterOfNode(root)
+    return diameter
+}