之字形打印二叉树

/*
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> > Print(TreeNode* pRoot) {
            vector<vector<int> > res;
            vector<int> res0;
        if(pRoot == NULL)
            return res;
        std::stack<TreeNode *> stack[2];
        int current = 0;
        int next = 1;
        stack[current].push(pRoot);
        while(!stack[0].empty()||!stack[1].empty())
        {
            TreeNode * pNode =stack[current].top();
            stack[current].pop();
            res0.push_back(pNode->val);
            if(current ==0)
            {
                if(pNode->left!=NULL)
                    stack[next].push(pNode->left);
                if(pNode->right!=NULL)
                    stack[next].push(pNode->right);
            }
            else{
                if(pNode->right!=NULL)
                    stack[next].push(pNode->right);
                if(pNode->left!=NULL)
                    stack[next].push(pNode->left);
            }
            if(stack[current].empty())
            {
                res.push_back(res0);
                current = 1-current;
                next = 1-next;
                res0.clear();                
            }
        }
        return res;
        
    }
    
};