利用递归处理
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<vector<int> >ans;
vector<vector<int> > pathSum(TreeNode *root, int sum) {
vector<int>v;
Sum(root,sum,v);
return ans;
}
void Sum(TreeNode *root, int sum, vector<int>res){
if(root == NULL) return ;
res.push_back(root->val);
if(root->val == sum && root->left == NULL && root->right == NULL)
ans.push_back(res);
Sum(root->left,sum-root->val,res);
Sum(root->right,sum-root->val,res);
}
};