Cod sursa(job #1091030)

Utilizator rzvrzvNicolescu Razvan rzvrzv Data 23 ianuarie 2014 14:42:30
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.34 kb
#include<cstdio>
#include<cstring>

using namespace std;

char s[100014],*p;
int n;

int eval();

int termen();

int factor();

int main()
{
    freopen("evaluare.in","r",stdin);
    freopen("evaluare.out","w",stdout);
    gets(s);
    p=s;
    n=eval();
    printf("%d\n",n);
    return 0;
}

int eval()
{
    int r;
    r=termen();
    while(*p=='+'||*p=='-')
    switch (*p)
    {
        case '+':
        {
            ++p;
            r+=termen();
            break;
        }
        case '-':
        {
            ++p;
            r-=termen();
            break;
        }
    }
    return r;
}

int termen()
{
    int r;
    r=factor();
    while(*p=='*'||*p=='/')
        switch(*p)
        {
            case '*':
            {
                    ++p;
                    r*=factor();
                    break;
            }
            case '/':
            {
                    ++p;
                    r/=factor();
                    break;
            }
        }
    return r;
}

int factor()
{
    int r;
    r=0;
    if(*p=='(')
        {
            ++p;
            r=eval();
            ++p;
    }
    else
    {
        while('0'<=*p && *p<='9')
        {
            r*=10;
            r+=(int)*p-'0';
            ++p;
        }
    }
    return r;
}