题目：

---

代码（首刷看解析，暴力法）：

class Solution {
public:
    long rootSum(TreeNode* root,long targetSum){
        if(!root) return 0;

        long res=0;
        if(root->val==targetSum){
            res++;
        } 

        res+=rootSum(root->left,targetSum-root->val);
        res+=rootSum(root->right,targetSum-root->val);
        return res;
    }
    long pathSum(TreeNode* root, long targetSum) {
        if(!root) return 0;
        long res =rootSum(root,targetSum);
        res+=pathSum(root->left,targetSum);
        res+=pathSum(root->right,targetSum);
        return res;
    }
};

        int类型大小不够，需要long