C语言非递归实现二叉树的先序、中序、后序、层序遍历

  1 #include <stdio.h>    
  2 #include <stdlib.h>   
  3 #include <stack>
  4 #include <queue>
  5 using namespace std;
  6 
  7 //*****二叉树的二叉链表存储表示*****//    
  8 typedef struct BiNode    
  9 {    
 10     char data;    
 11     struct BiNode *lchild, *rchild; 
 12     int visitCount;
 13 }BiNode, *BiTree;    
 14 
 15 //*****按先序次序输入二叉树中结点的值(一个字符)，空格字符表示空树构造二叉链表表示的二叉树T*****//     
 16 void CreateBiTree(BiTree &T)            
 17 {                                       
 18     char ch;    
 19     scanf("%c", &ch);    
 20     if(ch == ‘ ‘)    
 21     {    
 22         T = NULL;    
 23     }    
 24     else    
 25     {    
 26         if(!(T = (BiNode *)malloc(sizeof(BiNode))))     
 27         {    
 28             return;    
 29         }    
 30         T->data = ch;                            //生成根结点    
 31         T->lchild = NULL;
 32         T->rchild = NULL;
 33         CreateBiTree(T->lchild);                //构造左子树    
 34         CreateBiTree(T->rchild);                //构造右子树    
 35     }    
 36 
 37     return;    
 38 }    
 39 
 40 //*****先序遍历二叉树*****//     
 41 void PreOrderTraverse(BiTree T)    
 42 {    
 43     stack<BiTree> TreeStack;
 44     BiTree p = T;
 45 
 46     while (p || !TreeStack.empty())
 47     {
 48         if (p)
 49         {
 50             printf("%c ", p->data);
 51             TreeStack.push(p);
 52             p = p->lchild;
 53         }
 54         else
 55         {
 56             p = TreeStack.top();
 57             TreeStack.pop();
 58             p = p->rchild;
 59         }
 60     }
 61 }    
 62 
 63 //*****中序遍历二叉树*****//     
 64 void InOrderTraverse(BiTree T)    
 65 {    
 66     stack<BiTree> TreeStack;
 67     BiTree p = T;
 68 
 69     while (p || !TreeStack.empty())
 70     {
 71         if (p)
 72         {
 73             TreeStack.push(p);
 74             p = p->lchild;
 75         }
 76         else
 77         {
 78             p = TreeStack.top();
 79             printf("%c ", p->data);
 80             TreeStack.pop();
 81             p = p->rchild;
 82         }
 83     }
 84 }    
 85 
 86 //*****后序遍历二叉树*****//     
 87 void PostOrderTraverse(BiTree T)    
 88 {    
 89     stack<BiTree> TreeStack;
 90     BiTree p = T;
 91 
 92     while (p || !TreeStack.empty())
 93     {
 94         if (p)
 95         {
 96             p->visitCount = 1;
 97             TreeStack.push(p);
 98             p = p->lchild;
 99         }
100         else
101         {
102             p = TreeStack.top();
103             TreeStack.pop();
104             if (p->visitCount == 2)
105             {
106                 printf("%c ", p->data);
107                 p = NULL;
108             }
109             else
110             {
111                 p->visitCount++;
112                 TreeStack.push(p);
113                 p = p->rchild;
114             }
115         }
116     }
117 }  
118 
119 //*****层序遍历二叉树*****// 
120 void LevelOrderTraverse(BiTree T)
121 {
122     if (!T)
123     {
124         return;
125     }
126 
127     queue<BiTree> TreeQueue;
128     TreeQueue.push(T);
129     BiTree p = T;
130     while (!TreeQueue.empty())
131     {
132         p = TreeQueue.front();
133         TreeQueue.pop();
134         printf("%c ", p->data);
135 
136         if (p->lchild)
137         {
138             TreeQueue.push(p->lchild);
139         }
140         if (p->rchild)
141         {
142             TreeQueue.push(p->rchild);
143         }
144     }
145 }
146 
147 int main(void)    
148 {    
149     BiTree T;        
150     printf("请按先序次序输入二叉树中结点的值(字符)，空格字符表示空树:\n");    
151     CreateBiTree(T);        
152 
153     printf("先序遍历结果为:");    
154     PreOrderTraverse(T);    
155     printf("\n\n");     
156 
157     printf("中序遍历结果为:");    
158     InOrderTraverse(T);    
159     printf("\n\n");     
160 
161     printf("后序遍历结果为:");    
162     PostOrderTraverse(T);        
163     printf("\n\n");      
164 
165     printf("层序遍历结果为:");    
166     LevelOrderTraverse(T);        
167     printf("\n\n"); 
168 
169     return 0;        
170 }