solve problem

Author: delight010

same-tree/delight010.swift

@@ -0,0 +1,37 @@
+public class TreeNode {
+    public var val: Int
+    public var left: TreeNode?
+    public var right: TreeNode?
+    public init() { self.val = 0; self.left = nil; self.right = nil; }
+    public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
+    public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
+        self.val = val
+        self.left = left
+        self.right = right
+    }
+}
+
+class Solution {
+    // Time O(n)
+    // Space best O(log n)
+    // Space worst O(n)
+    func isSameTree(_ p: TreeNode?, _ q: TreeNode?) -> Bool {
+        return dfs(p, q)
+    }
+    
+    private func dfs(_ p: TreeNode?, _ q: TreeNode?) -> Bool {
+        if p == nil && q == nil {
+            return true
+        }
+        
+        guard let p = p else { return false }
+        guard let q = q else { return false }
+        
+        if p.val != q.val {
+            return false
+        }
+        
+        return dfs(p.left, q.left) && dfs(p.right, q.right)
+    }
+}
+