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 <queue>
#include <vector>
#include<algorithm>
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
        queue<TreeNode*> q;
        vector<vector<int>> re;
        if (pRoot) {
            q.push(pRoot);
        }
        int j=1;  //标志位，奇数层不变，偶数层反转
        while (!q.empty()) {
            int i=q.size();
            vector<int> num;
            while(i--){
                TreeNode* temp=q.front();
                num.push_back(temp->val);
                q.pop();
                if (temp->left) {
                    q.push(temp->left);
                }
                if (temp->right) {
                    q.push(temp->right);
                }
            }
            if (j%2==0) {
                reverse(num.begin(),num.end());
            }
            re.push_back(num);
            j++;
        }
        return re;
    }
};