Create leaf-similar-trees.cpp

Author: kamyu104

C++/leaf-similar-trees.cpp

@@ -0,0 +1,40 @@
+// Time:  O(n)
+// Space: O(h)
+
+/**
+ * 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 leafSimilar(TreeNode* root1, TreeNode* root2) {
+        vector<TreeNode*> s1{root1} , s2{root2};
+        while (!s1.empty() && !s2.empty()) {
+            if (dfs(s1) != dfs(s2)) {
+                return false;
+            }
+        }
+        return s1.empty() && s2.empty();
+    }
+
+private:
+    int dfs(vector<TreeNode*>& s) {
+        while (true) {
+            const auto node = s.back(); s.pop_back();
+            if (node->right) {
+                s.emplace_back(node->right);
+            }
+            if (node->left) {
+                s.emplace_back(node->left);
+            }
+            if (!node->left && !node->right) {
+                return node->val;
+            }
+        }
+    }
+};