Subtree Of Another Tree

Author: TonyKim9401

subtree-of-another-tree/TonyKim9401.java

@@ -0,0 +1,25 @@
+// TC: O(n)
+// need to check all nodes in the worst case
+// SC: O(n)
+// recursion requires O(n) SC in the worst case
+class Solution {
+    public boolean isSubtree(TreeNode root, TreeNode subRoot) {
+        if (root == null) return false;
+
+        if (sameCheck(root, subRoot)) return true;
+
+        return isSubtree(root.left, subRoot) ||
+                isSubtree(root.right, subRoot);
+    }
+
+    private boolean sameCheck(TreeNode root, TreeNode subRoot) {
+        if (root == null || subRoot == null) {
+            return root == null && subRoot == null;
+        }
+
+        if (root.val != subRoot.val) return false;
+
+        return sameCheck(root.left, subRoot.left) &&
+                sameCheck(root.right, subRoot.right);
+    }
+}