Leetcode——563. 二叉树的坡度

/**
 * 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:
    int sumValue(TreeNode* root,int& sum)
    {
        if(root==NULL)
            return 0;
        int left=sumValue(root->left,sum);
        int right=sumValue(root->right,sum);
        sum+=abs(left-right);
        return root->val+left+right;
    }
    int findTilt(TreeNode* root) 
    {
        if(root==NULL)
            return 0;
        int sum=0;
        sumValue(root,sum);
        return sum;
    }
};