题解 | #按之字形顺序打印二叉树#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
#include <vector>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param pRoot TreeNode类 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > Print(TreeNode* pRoot) {
        // write code here
        vector<vector<int>>res;
        queue<TreeNode*>q;
        if(pRoot==nullptr)
        {
            return res;
        }
        q.push(pRoot);
        int flag = 1;
        vector<int>temp;
        while(!q.empty())
        {
            int size = q.size();
            while(size--)
            {
                TreeNode* tmp = q.front(); // 队头元素
                q.pop(); 
                temp.push_back(tmp->val);

                if(tmp->left)
                {
                    q.push(tmp->left);
                }
                if(tmp->right)
                {
                    q.push(tmp->right);
                }
            }
            if(flag%2==0)
            {
                std::reverse(temp.begin(), temp.end());  //反转容器
                res.push_back(temp);
            }
            else {
                res.push_back(temp);
            }
            temp.clear();
            flag++;
        }
        return res;
    }
};