Implement maximum-level-sum-of-a-binary-tree

https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree

time: 224ms
time-rank: 79.82%
time-complexity: O(N)

space: 70.5MB
space-rank: 100%
space-complexity: O(N)

Author: cfriedt

maximum-level-sum-of-a-binary-tree-test.cpp

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+/*
+ * MIT License
+ *
+ * Copyright (c) 2018 Christopher Friedt
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <string>
+
+#include <gtest/gtest.h>
+
+#include "util/TreeNode.cpp"
+
+#include "maximum-level-sum-of-a-binary-tree.cpp"
+
+using namespace std;
+
+TEST( MaximumLevelSumOfABinaryTree, Test_empty ) {
+    TreeNode *root = TreeNode_from_string("[]");
+    int expected_int = 0;
+    int actual_int = Solution().maxLevelSum(root);
+    EXPECT_EQ( actual_int, expected_int );
+}
+
+TEST( MaximumLevelSumOfABinaryTree, Test_1_7_0_7_n8_null_null ) {
+    TreeNode *root = TreeNode_from_string("[1,7,0,7,-8,null,null]");
+    int expected_int = 2;
+    int actual_int = Solution().maxLevelSum(root);
+    EXPECT_EQ( actual_int, expected_int );
+}
+
+TEST( MaximumLevelSumOfABinaryTree, Test_989_null_10250_98693_n89388_null_null_null_n32127 ) {
+    TreeNode *root = TreeNode_from_string("[989,null,10250,98693,-89388,null,null,null,-32127]");
+    int expected_int = 2;
+    int actual_int = Solution().maxLevelSum(root);
+    EXPECT_EQ( actual_int, expected_int );
+}
+
+TEST( MaximumLevelSumOfABinaryTree, Test_5_3_2 ) {
+    TreeNode *root = TreeNode_from_string("[5,3,2]");
+    int expected_int = 1;
+    int actual_int = Solution().maxLevelSum(root);
+    EXPECT_EQ( actual_int, expected_int );
+}

maximum-level-sum-of-a-binary-tree.cpp

@@ -0,0 +1,85 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 Christopher Friedt
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+
+#include <algorithm>
+#include <climits>
+#include <unordered_map>
+#include <vector>
+
+using namespace std;
+
+// https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree/
+
+class Solution {
+public:
+    int maxLevelSum(TreeNode* root) {
+        unordered_map<size_t,int> level_sums;
+
+        if ( nullptr == root ) {
+            return 0;
+        }
+
+        calculateSums( level_sums, 1, root );
+
+        vector<size_t> levels( level_sums.size(), -1 );
+        size_t i = 0;
+        for( auto & kv: level_sums ) {
+            levels[ i++ ] = kv.first;
+        }
+
+        auto comparator = [&]( const size_t & a, const size_t & b ) -> bool {
+            if ( level_sums[ b ] > level_sums[ a ] ) {
+                return false;
+            }
+            if ( level_sums[ b ] < level_sums[ a ] ) {
+                return true;
+            }
+            return b > a;
+        };
+
+        sort( levels.begin(), levels.end(), comparator );
+
+        return levels[ 0 ];
+    }
+
+    static void calculateSums( unordered_map<size_t,int> & level_sums, const size_t level, const TreeNode *node ) {
+        if ( nullptr == node ) {
+            return;
+        }
+
+        calculateSums( level_sums, level + 1, node->left );
+        calculateSums( level_sums, level + 1, node->right );
+        level_sums[ level ] += node->val;
+    }
+};