二叉树路径之和：带记忆的DFS

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
public:
    vector<vector<int>> buffer;
    vector<int> tmp;
    vector<vector<int> > FindPath(TreeNode* root,int expectNumber) {
        if (root==NULL)
            return buffer;
        tmp.push_back(root->val);
        if(expectNumber==root->val && root->left==NULL && root->right==NULL)
            buffer.push_back(tmp);
        FindPath(root->left, expectNumber-root->val);
        FindPath(root->right, expectNumber-root->val);
        if(tmp.size()!=0)
            tmp.pop_back();
        return buffer;

    }
};