30daysOfCode/10-10-23-BinaryTreeMaximumPathSum.cpp at main · MatheusSanchez/30daysOfCode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
/*
    Time O(n) n ==  TREE.size()
    Space  O(h)  h == TREE.height()
    https://leetcode.com/problems/binary-tree-maximum-path-sum/description/
*/

class Solution {
public:
    int maxPathSum(TreeNode* root) {
        int maxPathSum = INT_MIN;
        pathSum(root, maxPathSum);
        return maxPathSum;
    }

    int pathSum(TreeNode* root, int &maxPathSum ) {

        if(root == nullptr){
            return 0;
        }


        int leftPath =  pathSum(root->left, maxPathSum);
        int rightPath = pathSum(root->right, maxPathSum);
        int maxPath = root->val + max(leftPath,rightPath);

        maxPath = max(maxPath, root->val);
        maxPath = max(maxPath, root->val+leftPath+rightPath);

        maxPathSum = max(maxPathSum,  maxPath);

        /*
        maxPathSum
        root->val + left,
        root->val + right,
        root->val + left + right,
        root->val

        // O(n)
        // O(h) == h altura da arvore;
        */


        return max(root->val + max(rightPath,leftPath), root->val);

    }


};