Cod sursa(job #1003213)

Utilizator manutrutaEmanuel Truta manutruta Data 29 septembrie 2013 22:26:20
Problema Evaluarea unei expresii Scor 10
Compilator cpp Status done
Runda Arhiva educationala Marime 1.18 kb
#include <iostream>
#include <fstream>
using namespace std;

#define MAXS 100010

ifstream f("evaluare.in");
ofstream g("evaluare.out");

char s[MAXS], *p = s;

int termen();
int factor();

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

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

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

int main()
{
    f >> s;
    g << eval();

    return 0;
}