[Tree] Update solution for Same Tree

Ngoys · Feb 15, 2018 · 6232cf9 · 6232cf9
1 parent 518b7f6
commit 6232cf9
Showing 1 changed file with 9 additions and 5 deletions.
diff --git a/Tree/SameTree.swift b/Tree/SameTree.swift
@@ -20,13 +20,17 @@
 
 class SameTree {
     func isSameTree(p: TreeNode?, _ q: TreeNode?) -> Bool {
-        if p == nil && q == nil {
-            return true
+        guard let p = p else {
+            return q == nil
         }
-        if p == nil || q == nil || p!.val != q!.val {
+        guard let q = q else {
+            return p == nil
+        }
+
+        if p.val != q.val {
             return false
         }
-    
-        return isSameTree(p!.left, q!.left) && isSameTree(p!.right, q!.right)
+
+        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right)
     }
 }