Create find-largest-value-in-each-tree-row.cpp

Author: kamyu104

C++/find-largest-value-in-each-tree-row.cpp

@@ -0,0 +1,64 @@
+// 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:
+    vector<int> largestValues(TreeNode* root) {
+        vector<int> result;
+        largestValuesHelper(root, 0, &result);
+        return result;
+    }
+private:
+    void largestValuesHelper(TreeNode* root, int depth, vector<int> *result) {
+        if (!root) {
+            return;
+        }
+        if (depth == result->size()) {
+            result->emplace_back(root->val);
+        } else {
+            (*result)[depth] = max((*result)[depth], root->val);
+        }
+        largestValuesHelper(root->left, depth + 1, result);
+        largestValuesHelper(root->right, depth + 1, result);
+    }
+ };
+ 
+// Time:  O(n)
+// Space: O(n)
+class Solution2 {
+public:
+    vector<int> largestValues(TreeNode* root) {
+        if (!root) {
+            return {};
+        }
+        vector<int> result;
+        vector<TreeNode*> curr, next;
+        curr.emplace_back(root);
+        while (!curr.empty()) {
+            int max_val = numeric_limits<int>::min();
+            next.clear();
+            for (const auto& node : curr) {
+                max_val = max(max_val, node->val);
+                if (node->left) {
+                    next.emplace_back(node->left);
+                }
+                if (node->right) {
+                    next.emplace_back(node->right);
+                }
+            }
+            result.emplace_back(max_val);
+            swap(curr, next);
+        }
+        return result;
+    }
+};