题解 | #把二叉树打印成多行# 经典层序遍历

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
#include <unistd.h>
#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
        // 首先想到层序遍历
        queue<TreeNode*> que;
        vector<vector<int>> res;
        if(pRoot == nullptr) return res;
        que.push(pRoot);
        while(!que.empty()){
            int n = que.size();
            vector<int> path;
            for(int i=0; i<n ;i++){
                TreeNode *node = que.front();
                que.pop();
                if(node -> left) que.push(node->left);
                if(node -> right) que.push(node->right);
                path.push_back(node->val);
            }
            res.push_back(path);
        }
        return res;
    }
};