【剑指Offer】（树）把二叉树打印成多行

约定不等于承诺〃 2022-03-16 01:00 172阅读 0赞

**题目链接**：[https://www.nowcoder.com/practice/7fe2212963db4790b57431d9ed259701?tpId=13&tqId=11175&tPage=2&rp=2&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking][https_www.nowcoder.com_practice_7fe2212963db4790b57431d9ed259701_tpId_13_tqId_11175_tPage_2_rp_2_ru_ta_coding-interviews_qru_ta_coding-interviews_question-ranking]

#### 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。

#### 解决方法 ####

/* 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) { 
            //层次遍历
            vector<vector<int>> res;
            if(!pRoot) return res;
            queue<TreeNode*> q;
            q.push(pRoot);
            while(!q.empty()){ 
                vector<int> resL;
                int len=q.size();
                while(len--){ 
                    TreeNode *temp=q.front(); q.pop();                
                    resL.push_back(temp->val);
                    if(temp->left) q.push(temp->left);
                    if(temp->right) q.push(temp->right);
                }
                res.push_back(resL);
            }
            return res;
        }    
    };

[https_www.nowcoder.com_practice_7fe2212963db4790b57431d9ed259701_tpId_13_tqId_11175_tPage_2_rp_2_ru_ta_coding-interviews_qru_ta_coding-interviews_question-ranking]: https://www.nowcoder.com/practice/7fe2212963db4790b57431d9ed259701?tpId=13&tqId=11175&tPage=2&rp=2&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking