437. Path sum III

Given the root node of a binary tree root , And an integer targetSum , Find that the sum of the node values in the binary tree is equal to targetSum Of route Number of .

route You don't need to start at the root node , It doesn't need to end at the leaf node , But the path has to be down （ Only from parent node to child node ）.

class Solution {

public:

    void f(TreeNode* root, int targetSum,vector<int>sum,int &count)

    {

        if(nullptr ==root)

        {

            return;

        }

        vector<int> tmp;

        for(auto it:sum)

        {

            tmp.push_back(it+root->val);

            if(it+root->val == targetSum)

            {

                count++;

            }

        }

        sum = tmp;

        sum.push_back(root->val);

        if(root->val == targetSum)

        {

            count++;

        }

        f(root->left, targetSum,sum,count);

        f(root->right, targetSum,sum,count);

    }

 

    int pathSum(TreeNode* root, int targetSum) {

        int ret=0;

        vector<int>sum;

        f(root,targetSum,sum,ret);

        return ret;

    }

};