给一个二叉树root和一个target值，求所有从根开始到叶节点的路径和等于target的路径。

class Solution {
public:
    void MoveOnPath(TreeNode *node,int sum,int &val,vector<int>&item,vector<vector<int>>&ans) {
        if(node == NULL)return;
        if(node->left == NULL && node->right == NULL) {
            if(sum == val)ans.push_back(item);
            return ;
        }
        if(node->left != NULL) {
            val += node->left->val;
            item.push_back(node->left->val);
            MoveOnPath(node->left,sum,val,item,ans);
            val -= node->left->val;
            item.pop_back();
        }
        if(node->right != NULL) {
            val += node->right->val;
            item.push_back(node->right->val);
            MoveOnPath(node->right,sum,val,item,ans);
            val -= node->right->val;
            item.pop_back();<br />
        }
    }
    vector&lt;vector&lt;int&gt; &gt; pathSum(TreeNode *root, int sum) {
        vector&lt;vector&lt;int&gt;&gt;ans;
        ans.clear();
        if(root == NULL)return ans;
        int val = 0;
        vector &lt;int&gt; item;
        item.clear();
        val += root-&gt;val;
        item.push_back(root-&gt;val);
        MoveOnPath(root,sum,val,item,ans);
        return ans;
    }
};