[恢]hdu 1237

2011-12-25 15:48:22

地址：http://acm.hdu.edu.cn/showproblem.php?pid=1237

题意：中文。

mark：用递归替代栈。1WA。开始没考虑到1 - 2 + 2的情况。把2+2先算了。。。

代码：

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


char str[1010] ;
double num[1010] ;
char op[1010] ;
int cnt ;


void getWord ()
{
    double buff = 0 ;
    int i, flag = 0 ;
    for (i = 0 ; str[i] ; i++)
    {
        if (flag == 0)
        {
            if (str[i] == ' ')
            {
                flag = 1 ;
                num[cnt] = buff ;
            }
            else buff = buff * 10 + (str[i] -'0') ;
        }
        else
        {
            op[cnt++] = str[i] ;
            buff = 0 ;
            i++ ;
            flag = 0 ;
        }
    }
    num[cnt] = buff ;
}


double fun(double a, double b, char op)
{
    double ans ;
    switch (op)
    {
        case '+':ans = a+b ; break ;
        case '-':ans = a-b ; break ;
        case '*':ans = a*b ; break ;
        case '/':ans = a/b ; break ;
    }
    return ans ;
}


double calc(int n)
{
    if (n == cnt-1)
        return fun(num[n], num[n+1], op[n]) ;
    if (op[n] == '+')
        return fun(num[n], calc(n+1), op[n]) ;
    if (op[n] == '-')
    {
        num[n+1] = -num[n+1] ;
        op[n] = '+' ;
        return fun(num[n], calc(n+1), op[n]) ;
    }
    num[n+1] = fun(num[n], num[n+1], op[n]) ;
    return calc(n+1) ;
}


double gao()
{
    cnt = 0 ;
    getWord() ;
    return calc(0) ; ;
}


int main ()
{
    while (gets(str) && strcmp (str, "0"))
        printf ("%.2lf\n", gao()) ;
    return 0 ;
}