Cod sursa(job #2529887)

Utilizator alex_braslasuBraslasu Alexandru alex_braslasu Data 24 ianuarie 2020 09:26:02
Problema Evaluarea unei expresii Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1 kb
#include <iostream>
#include <fstream>
#include <cstring>

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

char s[100005], *p;

int eval();
int termen();
int factor();

int eval()
{
    int r = termen();
    while (*p == '+' || *p == '-')
    if (*p == '+')
    {
        ++p;
        r += termen();
    }
    else
    {
        ++p;
        r -= termen();
    }
    return r;
}

int termen()
{
    int r = factor();
    while (*p == '*' || *p == '/')
    if (*p == '*')
    {
        ++p;
        r *= factor();
    }
    else
    {
        ++p;
        r /= factor();
    }
    return r;
}

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

int main()
{
    f >> s;
    p = s;
    g << eval();
    return 0;
}