LeetCode437(路径总和)

题目链接:https://leetcode-cn.com/problems/path-sum-iii/

/**
 * 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 pathSum(TreeNode* root, int sum) {
       int count = 0;
        if(!root)
            return count;
        return generate(sum,root)+pathSum(root->left,sum)+pathSum(root->right,sum);
    }
private:
    int generate(int sum,TreeNode* node)
    {
        int count = 0;
        if(node == NULL)
            return count;
        if(node->val == sum)
            count++;
        count += generate(sum-node->val,node->left);
        count += generate(sum-node->val,node->right);
        return count;       
    }
};