Create subtree-of-another-tree.cpp

Author: kamyu104

C++/subtree-of-another-tree.cpp

@@ -0,0 +1,37 @@
+// Time:  O(m * n), m is the number of nodes of s, n is the number of nodes of t
+// Space: O(h), h is the height of s
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    bool isSubtree(TreeNode* s, TreeNode* t) {
+        return preOrderTraverse(s, t);
+    }
+
+private:
+    bool preOrderTraverse(TreeNode *s, TreeNode *t) {
+        return s && (isSame(s, t) ||
+                     preOrderTraverse(s->left, t) ||
+                     preOrderTraverse(s->right, t));
+    }
+
+    bool isSame(TreeNode *x,TreeNode *y) {
+        if (!x && !y) {
+            return true;
+        }
+        if (!x || !y) {
+            return false;
+        }
+        return x->val == y->val &&
+               isSame(x->left, y->left) &&
+               isSame(x->right, y->right);
+    }
+};