思路：此题思路为递归实现，递归思路为：在每层递归的过程中将各个节点的数据记录下来，不断将减少目标数据的值准备进行判断，当进行到叶子节点时要进行判断

/*** Definition for a binary tree node.* struct TreeNode {*     int val;*     struct TreeNode *left;*     struct TreeNode *right;* };*/
bool hasPathSum(struct TreeNode* root, int targetSum) {if(root==NULL){return false;}int sum=root->val;if(root->left==NULL&&root->right==NULL){return targetSum==sum;}return hasPathSum(root->left,targetSum-sum)||hasPathSum(root->right,targetSum-sum);
}