剑指offer---把二叉树打印成多行

Posted 2021-01-16 iwangzhengchao

题目：把二叉树打印成多行

要求：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。

/*
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) {
        
        }
    
};

 

解题代码：

 1 class Solution {
 2 public:
 3     vector<vector<int> > Print(TreeNode* pRoot) {
 4         vector<vector<int> > res;
 5         vector<int> subRes;
 6         if(pRoot == nullptr)
 7             return res;
 8 
 9         int currentLevel = 1;
10         int nextLevel = 0;
11         queue<TreeNode*> q;
12         q.push(pRoot);
13 
14         while(!q.empty()){
15             TreeNode* temp = q.front();
16             subRes.push_back(temp->val);
17             q.pop();
18 
19             if(temp->left){
20                 q.push(temp->left);
21                 nextLevel++;
22             }
23             if(temp->right){
24                 q.push(temp->right);
25                 nextLevel++;
26             }
27             currentLevel--;
28             if(currentLevel == 0){
29                 res.push_back(subRes);
30                 subRes.clear();
31                 currentLevel = nextLevel;
32                 nextLevel = 0;
33             }
34         }
35         return res;
36     }
37 };