2006年第5题

题目地址：http://jobdu.sinaapp.com/problem.php?cid=1040&pid=26

C语言源码：

#include<stdio.h>
#include<string.h>
#define maxsize 300
int precede(char a,char b)
{
	int m[5][5]={{-1,-1,-1,-1,1},{-1,-1,-1,-1,1},{1,1,-1,-1,1,},{1,1,-1,-1,1},{-1,-1,-1,-1,0}};//+,-,*,/
	int i,j;
	switch(a)
	{
	case '+':i=0;break;
	case '-':i=1;break;
	case '*':i=2;break;
	case '/':i=3;break;
	default :i=4;break;
	}
	switch(b)
	{
    case '+':j=0;break;
	case '-':j=1;break;
	case '*':j=2;break;
	case '/':j=3;break;
	default :j=4;break;
	}
	return m[i][j];
}
double operate(double a,char s,double b)
{
	switch(s)
	{
	case '+':return a+b;
	case '-':return a-b;
	case '*':return a*b;
	case '/':return a/b;
	}
}
int main()
{
	int topfu,topshu,i,x,len;
	double shu[maxsize],a,b;
	char fu[maxsize],s[maxsize],y;
	gets(s);
	while(1)
	{
		if(s[0]=='0'&&s[1]=='\0')
			break;
		len=(int)strlen(s);
		s[len]='#';
		s[len+1]='\0';
		topfu=0;
		topshu=0;
		fu[topfu++]='#';
		i=0;
		x=0;
		while(s[i]!='\0')
		{
			if(s[i]>='0'&&s[i]<='9')
				x=x*10+s[i]-'0';
			else
			{
				if(s[i]!=' ')
				{
					shu[topshu++]=x;
					x=0;
					while(precede(s[i],fu[topfu-1])<0)
					{
						topshu--;
						b=shu[topshu];
						topshu--;
						a=shu[topshu];
						topfu--;
						y=fu[topfu];
						shu[topshu++]=operate(a,y,b);
					}
					if(s[i]!='#')
						fu[topfu++]=s[i];
				}
			}
			i++;
		}
		printf("%.2lf\n",shu[topshu-1]);
		gets(s);
	}
}