题解 | #农场最大产奶牛群#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int pathmax(TreeNode* root, int& sum)
    {
        if (root == nullptr)
            return 0;
        int left = pathmax(root->left, sum);
        int right = pathmax(root->right, sum);
        int path = left + right + root->val;
        sum = max(sum, path);
        return max(left, right) + root->val;
    }

    int maxMilkSum(TreeNode* root) {
        // write code here
        int sum = 0;
        pathmax(root, sum);
        return sum;
    }
};