剑指offer之 把二叉树打印成多行

题目描述

从上到下按层打印二叉树，同一层结点从左至右输出。每一层输出一行。

思路

利用队列的思想

代码

class Solution {
public:
    vector<vector<int> > Print(TreeNode* pRoot) {
        vector<vector<int> > res;
        vector<int> res_p;
        if(pRoot == NULL)
            return res;
        
        queue<TreeNode*> q_Tree;
        q_Tree.push(pRoot);
        res_p.push_back(pRoot->val);
        res.push_back(res_p);
        res_p.clear();
        int count = 1;
        
        while(q_Tree.size()>0)
        {
            int number = q_Tree.size();
            while(number > 0)
            {
                TreeNode* current = q_Tree.front();
                q_Tree.pop();
                if(current->left)
                {
                    q_Tree.push(current->left);
                    res_p.push_back(current->left->val);
                }
                if(current->right)
                {
                    q_Tree.push(current->right);
                    res_p.push_back(current->right->val);
                }
                number--;
            }
            if(res_p.size()>0)
            {
                res.push_back(res_p);
                res_p.clear();
            }
            count++;
        }
        return res;
    }
};