Add Solution.java to problems 0572

Author: huaxu1024

solution/0572.Subtree of Another Tree/Solution.java

@@ -0,0 +1,29 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public boolean isSubtree(TreeNode s, TreeNode t) {
+
+        if (t == null) return true;
+        if (s == null) return false;
+
+        if (s.val != t.val){
+            return isSubtree(s.left, t) || isSubtree(s.right, t);
+        }
+        return isSameTree(s, t) || isSubtree(s.left, t) || isSubtree(s.right, t);
+    }
+
+    private boolean isSameTree(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 isSameTree(root1.left, root2.left) && isSameTree(root1.right, root2.right);
+    }
+}