Cod sursa(job #1151403)

Utilizator andreiblaj17Andrei Blaj andreiblaj17 Data 24 martie 2014 09:14:42
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.08 kb
#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;

#define nmax 100005
ifstream in("evaluare.in");
ofstream out("evaluare.out");

char S[nmax], *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(){
    
    in >> p;
    out << eval();
    
    return 0;
}