int val;

TreeNode *left;

TreeNode *right;

TreeNode(int x) : val(x), left(NULL), right(NULL) {}

vector<vector<int>> res;

int sum;

vector<vector<int>> pathSum(TreeNode* root, int sum) {

vector<int> stack;

this->sum = sum;

order(root, stack, 0);

return res;

}

void order(TreeNode* root, vector<int>& stack,int sum) {

if (root != nullptr) {

stack.push_back(root->val);

sum += root->val;

if (root->left || root->right) { // 是否是根节点

order(root->left, stack, sum);

order(root->right, stack, sum);

} else {

if (sum == this->sum) {

this->res.push_back(stack); // push_back为拷贝操作

}

}

stack.pop_back();

}

}