Cod sursa(job #1539497)

Utilizator gavrisraulRaul Gavris gavrisraul Data 30 noiembrie 2015 21:16:30
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.1 kb
#include <fstream>
using namespace std;

ifstream fin("evaluare.in");
ofstream fout("evaluare.out");

const long MAX = 100010;
char S[MAX], *p=S;

long termen();
long factor();

long eval() {
    long r = termen();
    while ( *p=='+' || *p=='-' ) {
        switch ( *p ) {
            case '+':
                ++p;
                r += termen();
                break;
            case '-':
                ++p;
                r -= termen();
                break;
        }
    }
    return r;
}
long termen() {
    long r = factor();
    while ( *p=='*' || *p=='/' ) {
        switch ( *p ) {
            case '*' :
                ++p;
                r *= factor();
                break;
            case '/':
                ++p;
                r /= factor();
                break;
        }
    }
    return r;
}
long factor() {
    long r=0;
    if ( *p == '(' ) {
        ++p;
        r = eval();
        ++p;
    } else {
        while ( *p>='0' && *p<='9' )  {
            r = r*10 + *p - '0';
            ++p;
        }
    }
    return r;
}

int main() {
    fin.get(S,MAX);
    fout<<eval();
    return 0;
}