CodingInterview-把二叉树打印成多行

使用层序遍历，并使用两个指针跟踪每一层的 Node 个数即可。

/*
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>> result;
            if(pRoot==NULL) return result;
            queue<TreeNode*> q;
            q.push(pRoot);
            int now=1,next=0;
            vector<int>* v=new vector<int>();
            while(!q.empty()){
                TreeNode* t=q.front();
                q.pop();
                now--;
                v->push_back(t->val);
                if(t->left!=NULL) {
                    q.push(t->left);
                    next++;
                }
                if(t->right!=NULL) {
                    q.push(t->right);
                    next++;
                }
                if(now==0){
                    now=next;
                    next=0;
                    result.push_back(*v);
                    v=new vector<int>();
                }
            }
            return result;
        }

};