#229 Subtree of Another Tree

Author: forest000014

subtree-of-another-tree/forest000014.java

@@ -0,0 +1,48 @@
+/*
+# Time Complexity: O(n)
+# Space Complexity: O(n)
+  - 재귀 호출 파라미터 O(n) 사이즈 공간 필요
+*/
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    public boolean isSubtree(TreeNode root, TreeNode subRoot) {
+        return dfs(root, subRoot);
+    }
+
+    private boolean dfs(TreeNode root, TreeNode subRoot) {
+        if (root == null && subRoot == null) return true;
+        if (root == null || subRoot == null) return false;
+
+        if (root.val == subRoot.val) {
+            if (compareTrees(root, subRoot)) return true;
+        }
+
+        if (dfs(root.left, subRoot)) return true;
+        if (dfs(root.right, subRoot)) return true;
+
+        return false;
+    }
+
+    private boolean compareTrees(TreeNode root1, TreeNode root2) {
+        if (root1 == null && root2 == null) return true;
+        if (root1 == null || root2 == null) return false;
+        if (root1.val != root2.val) return false;
+
+        return compareTrees(root1.left, root2.left) && compareTrees(root1.right, root2.right);
+    }
+}