Cod sursa(job #255901)

Utilizator DraStiKDragos Oprica DraStiK Data 10 februarie 2009 20:51:20
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.05 kb
#include <stdio.h>
#define ll long 
#define DIM 100010
char a[DIM],*p=a;
ll eval ();
ll termen ();
ll factor ();
int main ()
{
    freopen ("evaluare.in","r",stdin);
    freopen ("evaluare.out","w",stdout);    
    fgets (a,DIM,stdin);
    printf ("%ld",eval ());
    return 0;
}
ll eval ()
{
    ll r;
    r=termen ();
    while (*p=='+' || *p=='-')
    {
        switch ( *p ) 
        {
			case '+':
				++p;						
				r += termen(); 
				break;
			case '-':
				++p;						
				r -= termen();
				break;
		}
    }
    return r;
}
ll termen ()
{
    ll r;
    r=factor ();
    while (*p=='*' || *p=='/')
    {
        switch ( *p ) 
        {
			case '*' :
				++p;
				r *= factor();
				break;
			case '/':
				++p;
				r /= factor();
				break;
		}
    }
    return r;
}
ll factor ()
{
    ll r=0;
    if (*p=='(')
    {
        ++p;
        r=eval ();
        ++p;
    }
    else
        while (*p>='0' && *p<='9')
        {
            r=r*10+*p-'0';
            ++p;
        }
    return r;
}