[LeetCode] Path Sum II

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5
             / \
            4   8
           /   / \
          11  13  4
         /  \    / \
        7    2  5   1

return

[
   [5,4,11,2],
   [5,8,4,5]
]

与上题一样，继续DFS.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
private:
    vector<vector<int> > ret;
public:
    void dfs(TreeNode *node, int sum, int curSum, vector<int> a)
    {
        if (node == NULL)
            return;
        
        if (node->left == NULL && node->right == NULL)
        {
            if (curSum + node->val == sum)
            {
                a.push_back(node->val);
                ret.push_back(a);
            }
            return;
        }
        
        a.push_back(node->val);
        dfs(node->left, sum, curSum + node->val, a);
        dfs(node->right, sum, curSum + node->val, a);
    }
    
    vector<vector<int> > pathSum(TreeNode *root, int sum) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        ret.clear();
        vector<int> a; 
        dfs(root, sum, 0, a);
        return ret;
    }
};