二叉树和栈构建的表达式树

 1 #ifndef _btree_h_
 2 #define _btree_h_
 3 
 4 #include "iostream"
 5 #include "stdlib.h"
 6 
 7 typedef struct _btree_
 8 {
 9     char data;
10     struct _btree_ *leftTree;
11     struct _btree_ *rightTree;
12 }BTree;
13 
14 /*初始化根节点，返回的是根节点地址*/
15 BTree*
16 initRoot(const char &data)
17 {
18     BTree *root = (BTree *)malloc(sizeof(BTree));
19     root->data = data;
20     root->leftTree = nullptr;
21     root->rightTree = nullptr;
22     return root;
23 }
24 
25 /*打印出所有节点的数据*/
26 void
27 printOut(BTree *root)
28 {
29     if (root->leftTree)
30     {
31         printOut(root->leftTree);
32     }
33 
34     if (root)
35         std::cout << root->data << std::endl;
36     else
37         return;
38 
39     if (root->rightTree)
40     {
41         printOut(root->rightTree);
42     }
43 }
44 
45 #endif //btree_h

 1 #ifndef _stack_h_
 2 #define _stack_h_
 3 
 4 #include "iostream"
 5 #include "stdlib.h"
 6 #include "btree.h"
 7 
 8 #define  minSize 5
 9 #define  emptyStack -1
10 
11 #define log(s); std::cout<<s<<std::endl;
12 
13 typedef struct _stack_
14 {
15     int capacity;
16     int topOfStack;
17     BTree* *Array;//注意数组保存的是指向BTree的指针，Array是指向数组的指针
18 }stack;
19 
20 stack *createStack(int maxSize)
21 {
22     stack *s;
23     if (maxSize < minSize)
24     {
25         log("Stack size is too small");
26     }
27     s = (stack *)malloc(sizeof(stack));
28     s->Array = (BTree **)malloc(sizeof(BTree *) * maxSize);
29     s->capacity = maxSize;
30     s->topOfStack = emptyStack;/*初始化为空栈*/
31     return s;
32 }
33 
34 int isFull(stack *s)/*检测是否为满栈*/
35 {
36     if (s == nullptr)
37     {
38         log("the stack has not inital");
39         return 1;
40     }
41     return s->topOfStack == s->capacity;
42 }
43 
44 int isEmpty(stack *s)/*是否为空栈*/
45 {
46     if (s == nullptr)
47     {
48         log("the stack has not inital");
49         return 1;
50     }
51     return s->topOfStack == emptyStack;
52 }
53 
54 void push(stack *s, BTree *&data)/*压栈*/ /*此处data是对BTree类型的引用*/
55 {
56     if (isFull(s))
57     {
58         log("Full of Stack");
59         return;
60     }
61     ++s->topOfStack;
62     s->Array[s->topOfStack] = data;
63 }
64 
65 void pop(stack *s)/*弹出栈*/
66 {
67     if (isEmpty(s))
68     {
69         log("Out of Stack");
70         return;
71     }
72     --s->topOfStack;
73 }
74 
75 BTree* top(stack *s)/*访问栈顶元素*/
76 {
77     if (isEmpty(s))
78     {
79         std::cout << "Out of Stack,Code is ";
80         return nullptr;
81     }
82     return s->Array[s->topOfStack];
83 }
84 
85 void makeEmpty(stack *&s)/*置空栈*/
86 {
87     free(s->Array);
88     free(s);
89     s = nullptr;
90 }
91 
92 #endif /*stack_h*/

 1 #include "btree.h"
 2 #include "stack.h"
 3 #include "iostream"
 4 #include "stdlib.h"
 5 
 6 int isSymbal(const char &c)
 7 {
 8     if (c == ‘+‘ || c == ‘-‘ || c == ‘/‘ || c == ‘*‘)
 9         return 1;
10     else
11         return 0;
12 }
13 
14 int main(void)
15 {
16     stack *s = createStack(20);
17     BTree *new_b = nullptr;
18     char c;
19     while (std::cin >> c)
20     {
21         if (c == ‘=‘)
22             break;
23         new_b = initRoot(c);
24         if (!isSymbal(c))//如果读入的不是符号，将枝叶的地址入栈
25             push(s, new_b);
26         else//如果读入的是符号
27         {
28             new_b->rightTree = top(s);//将栈顶的地址赋给右子树，后弹栈，将新栈顶赋给左子树，再弹栈，将新生成的根节点入栈
29             pop(s);
30             new_b->leftTree = top(s);
31             pop(s);
32             push(s, new_b);
33         }
34     }
35     printOut(top(s));
36     free(new_b);
37     makeEmpty(s);
38     system("pause");
39     return 0;
40 }