Create pseudo-palindromic-paths-in-a-binary-tree.cpp

Author: kamyu104

C++/pseudo-palindromic-paths-in-a-binary-tree.cpp

@@ -0,0 +1,52 @@
+// Time:  O(n)
+// Space: O(h)
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+
+class Solution {
+public:
+    int pseudoPalindromicPaths (TreeNode* root) {
+        int result = 0;
+        vector<pair<TreeNode *, int>> stk = {{root, 0}};
+        while (!stk.empty()) {
+            auto [node, count] = stk.back(); stk.pop_back();
+            if (!node) {
+                continue;
+            }
+            count ^= 1 << node->val;
+            result += int(!node->left && !node->right && (count & (count - 1)) == 0);
+            stk.emplace_back(node->right, count);
+            stk.emplace_back(node->left, count);
+        }
+        return result;
+    }
+};
+
+// Time:  O(n)
+// Space: O(h)
+class Solution2 {
+public:
+    int pseudoPalindromicPaths (TreeNode* root) {
+        return dfs(root, 0);
+    }
+
+private:
+    int dfs(TreeNode *node, int count) {
+        if (!node) {
+            return 0;
+        }
+        count ^= 1 << node->val;
+        return int(!node->left && !node->right && (count & (count - 1)) == 0) +
+               dfs(node->left, count) + dfs(node->right, count);
+    }
+};