Cod sursa(job #2100521)

Utilizator TavinciStefanescu Octavian Tavinci Data 5 ianuarie 2018 19:39:36
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.16 kb
#include <fstream>
#include <string>
using namespace std;

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

string s;
int termen(int &ind);
int factor(int &ind);
int eval(int &ind);
bool is_op1(char l)
{
    if(l=='+' || l=='-')
        return 1;
    return 0;
}
bool is_op2(char l)
{
    if(l=='*' || l=='/')
        return 1;
    return 0;
}
int factor(int &ind)
{
    if(s[ind]=='(')
    {
        ind++;
        int sum=eval(ind);
        ind++;
        return sum;
    }
    int nr=0;
    while(ind<=s.size() && isdigit(s[ind]))
    {
        nr=nr*10+s[ind++]-'0';
    }

    return nr;
}
int termen(int &ind)
{
    int p=factor(ind);
    while(ind!=s.size() && is_op2(s[ind]))
    {
        if(s[ind]=='*')
            p*=factor(++ind);
        else
            p/=factor(++ind);
    }
    return p;
}
int eval(int &ind)
{
    int sign;
    int a=termen(ind);
    while(ind!=s.size() && is_op1(s[ind]))
    {
        sign=1;
        if(s[ind]=='-')
            sign=-1;
        a+=sign*termen(++ind);
    }
    return a;
}

int main()
{
    fin>>s;
    int i=0;
    fout<<eval(i);
    return 0;
}