Cod sursa(job #837399)

Utilizator mvcl3Marian Iacob mvcl3 Data 17 decembrie 2012 22:41:10
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.05 kb
#include<fstream>
#define NMAX 100005
using namespace std;
ifstream f("evaluare.in"); ofstream g("evaluare.out");
char s[NMAX], *p;
int eval();
int termen();
int factor();
int main()
{
    f>>s;
    p = s;
    int rez = eval();
    g<<rez<<'\n';
    g.close();
    return 0;
}
int eval()
{
    int r = termen();
    while(*p == '+' || *p == '-')
    {
        switch(*p)
        {
            case '+' : {++p; r += termen(); break;}
            case '-' : {++p; r -= termen(); break;}
        }
    }
    return r;
}
int termen()
{
    int r = factor();
    while(*p == '*' || *p == '/')
    {
        switch(*p)
        {
            case '*' : {++p; r *= factor(); break;}
            case '/' : {++p; r /= factor(); break;}
        }
    }
    return r;
}
int factor()
{
    int r = 0;
    if(*p == '(')
    {
        ++p;
        r = eval();
        ++p;
    }
    else
    {
        while('0' <= *p && *p <= '9')
        {
            r = r  * 10 + *p - '0';
            ++p;
        }
    }
    return r;
}