编程之美——二叉树层次遍历

  1 #include<iostream>
  2 #include<queue>
  3 #include<vector>
  4 using namespace std;
  5 
  6 template<class T>
  7 class binaryTree
  8 {
  9     struct node
 10     {
 11         T elem;
 12         node *left;
 13         node *right;
 14 
 15         node(const T &x,node *lt=NULL,node *rt=NULL)
 16         :elem(x),left(lt),right(rt){}
 17         ~node(){}
 18     };
 19 
 20 private:
 21     node *root;
 22     void makeEmpty(node *&t);
 23     void levelTraverse(node *&t);
 24 public:
 25     binaryTree(node *t=NULL)
 26     {
 27         root=t;
 28     }
 29     void createBinaryTree();
 30     void levelTraverse()
 31     {
 32         levelTraverse(root);
 33     }
 34     ~binaryTree()
 35     {
 36         makeEmpty(root);
 37     }
 38 };
 39 
 40 //使用队列构造一个二叉查找树
 41 template<class T>
 42 void binaryTree<T>::createBinaryTree()
 43 {
 44     queue<node *>que;
 45     node *t;
 46     T value;
 47 
 48     cout<<"enter root:(-1 represent NULL)"<<":";
 49     cin>>value;
 50 
 51     root=new node(value);
 52     que.push(root);
 53 
 54     T ldata,rdata;
 55 
 56     while(!que.empty())
 57     {
 58         t=que.front();
 59         que.pop();
 60 
 61         cout<<"enter left son of the node "<<t->elem<<":";
 62         cin>>ldata;
 63         cout<<"enter right son of the node "<<t->elem<<":";
 64         cin>>rdata;
 65 
 66         if(ldata!=-1)
 67             que.push(t->left=new node(ldata));
 68         if(rdata!=-1)
 69             que.push(t->right=new node(rdata));
 70     }
 71     cout<<"construct complement!"<<endl;
 72 }
 73 
 74 template<class T>
 75 void binaryTree<T>::makeEmpty(node *&t)
 76 {
 77     if(t->left!=NULL)
 78         makeEmpty(t->left);
 79     if(t->right!=NULL)
 80         makeEmpty(t->right);
 81     delete t;
 82 }
 83 
 84 template<class T>
 85 void binaryTree<T>::levelTraverse(node *&t)
 86 {
 87     if(t==NULL)
 88         return;
 89 
 90     vector<node *>arr;
 91     int cur=0;
 92     int last=1;
 93 
 94     arr.push_back(t);
 95     while(cur<last)
 96     {
 97         while(cur<last)
 98         {
 99             cout<<arr[cur]->elem<<‘\t‘;
100             if(arr[cur]->left!=NULL)
101                 arr.push_back(arr[cur]->left);
102             if(arr[cur]->right!=NULL)
103                 arr.push_back(arr[cur]->right);
104             ++cur;
105         }
106 
107         last=arr.size();
108         cout<<endl;
109     }
110 }
111 
112 int main()
113 {
114     binaryTree<int>tree;
115     tree.createBinaryTree();
116     tree.levelTraverse();
117     return 0;
118 }

 1 template<class T>
 2 void binaryTree<T>::levelTraverse(node *&t)
 3 {
 4     queue<node *>que;
 5     que.push(t);
 6     while(!que.empty())
 7     {
 8         node *q=que.front();
 9         cout<<q->elem<<ends;
10         if(q->left!=NULL)
11             que.push(q->left);
12         if(q->right!=NULL)
13             que.push(q->right);
14         que.pop();
15     }
16 }

 1 template<class T>
 2 void binaryTree<T>::levelTraverse(node *&t)
 3 {
 4     queue<node *>que;
 5     node *sign;
 6     //标记值
 7     sign->elem=-1;
 8     que.push(t);
 9     que.push(sign);
10     while(que.size()>1)
11     {
12         node *q=que.front();
13         cout<<q->elem<<ends;
14         if(q->left!=NULL)
15             que.push(q->left);
16         if(q->right!=NULL)
17             que.push(q->right);
18         que.pop();
19 
20         //若遇到标记值，出对，入队，输出换行，开始下一层遍历
21         if(que.front()->elem==-1)
22         {
23             que.pop();
24             que.push(sign);
25             cout<<endl;
26         }
27     }
28 }