逆波兰表达式（严7.38）

Description

一个四则运算算术表达式以有向无环图的邻接表方式存储，每个操作数原子都由单个字母表示。编写程序输出其逆波兰表达式。

Input

输入四则运算算术表达式。

Output

输出其逆波兰表达式。

• Sample Input 

  (a+b)*c

• Sample Output

  ab+c*

这个题要求是用有向无环图，老师说可以不用，我就没用~

前面写的那个逆波兰代码大概是有点问题，过不了这道题，所以改了一下……

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

typedef struct Stack{
    char data;
    struct Stack *next;
    struct Stack *top;
    struct Stack *bottom;
}Stack;

Stack *create()
{
    Stack *q=(Stack *)malloc(sizeof(Stack));
    q->bottom = (Stack*) malloc (sizeof(Stack));
    q->bottom->next = NULL;
    q->top = q->bottom;
    return q;
}

char getTop(Stack *s)
{
    return s->top->data;
}

void pop(Stack *s)
{
    Stack *q=s->top;
    s->top=s->top->next;
    free(q);
}

void push(Stack *s,char b){
    Stack *q=(Stack *)malloc(sizeof(Stack));
    q->data=b;
    q->next=s->top;
    s->top=q;
}

int judge(char a, char b){
    if((a == '*' && (b == '+' || b == '-')) || (a == '/' && (b == '+' || b == '-')))
        return 1;
    else
        return 0;
}

int main()
{
    char str[205];
    char ans[205];
    scanf("%s",&str);
    int i;
    Stack *s=create();
    int s1=strlen(str);
    for(i=0;i<s1;i++)
    {
        if(str[i]>='a'&&str[i]<='z')
        {
            printf("%c",str[i]);
        }
        else if(str[i]=='(')
        {
            push(s,str[i]);
        }
        else if(str[i]==')')
        {
            char top = getTop(s);
            while(top != '(')
            {
                printf("%c",top);
                pop(s);
                top = getTop(s);
            }
            pop(s);
        }
        else
        {
            while(1)
            {
                char top = getTop(s);
                if(judge(str[i], top) || s->top == s->bottom || top == '(')
                {
                    push(s, str[i]);
                    break;
                }
                else if(top == '+' || top == '-' || top == '*' || top == '/')
                {
                    printf("%c",top);
                    pop(s);
                }
                else
                {
                    break;
                }
            }
        }
    }
    while(s->top != s->bottom)
    {
        int top = getTop(s);
        printf("%c",top);
        pop(s);
    }
    printf("\n");
    return 0;
}