1 #include <iostream>
2 #include <vector>
3 #include <queue>
4 using namespace std;
5
6 void Print(const vector<int> &v)
7 {
8 for(auto it:v)
9 {
10 cout<<it<<" ";
11 }
12 cout<<endl;
13 }
14 struct Treenode//定义树的节点
15 {
16 int val;
17 Treenode* left;
18 Treenode* right;
19 Treenode(int _val):val(_val),left(nullptr),right(nullptr){}
20 };
21 //[in] 树的根节点
22 //[out] 一维vector的层次遍历结果
23 //层次遍历关键在于queue的使用
24 vector<int> cenci(Treenode* root)
25 {
26 vector<int> result;
27 queue<Treenode*> que;
28 //if(root==nullptr) return nullptr;
29 que.push(root);
30 while(!que.empty())
31 {
32 Treenode* node=que.front();
33 que.pop();
34 if(node->left) que.push(node->left);
35 if(node->right) que.push(node->right);
36 result.push_back(node->val);
37 }
38 return result;
39 }
40 //[in]树的根节点
41 //[out]二维vector的层次遍历结果
42 vector<vector<int>> bianli(Treenode* root)
43 {
44 vector<vector<int>> result;//返回结果
45 queue<Treenode*> que;
46 que.push(root);
47
48 while(!que.empty())
49 {
50 vector<int> v;
51 size_t size=que.size();//当前行节点个数
52 for(size_t i=0;i<size;++i)//当前行节点的所有子节点加入队列
53 {
54 Treenode* node=que.front();
55 que.pop();
56 if(node->left) que.push(node->left);
57 if(node->right) que.push(node->right);
58 v.push_back(node->val);
59 }
60 result.push_back(v);
61 }
62 return result;
63
64 }
65 int main(int argc, char *argv[])
66 {
67
68 Treenode *t1=new Treenode(2);
69 Treenode *t2=new Treenode(3);
70 Treenode *t3=new Treenode(4);
71 Treenode *t4=new Treenode(5);
72 t1->left=t2;
73 t1->right=t3;
74 t2->left=t4;
75 //vector<int> result= cenci(t1);
76 //Print(result);
77 vector<vector<int>> result=bianli(t1);
78 for(auto it:result)//遍历输出结果
79 {
80 for(auto it2:it)
81 {
82 cout<<it2<<" ";
83 }
84 }
85 return 0;
86 }
