力扣563 二叉樹坡度 遞歸

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/**
 * 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 {
    int sum=0;
public:
    int mod(TreeNode* root)
    {
        if(root==nullptr) return 0;
        int left=mod(root->left);
        int right=mod(root->right);
        sum+=abs(left-right);
        return left+right+root->val;
    }
    int findTilt(TreeNode* root) {
        mod(root);
        return sum;
    }
};