Cod sursa(job #1246598)

Utilizator codi22FMI Condrea Florin codi22 Data 21 octombrie 2014 12:49:25
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.51 kb
#include <iostream>
#include <fstream>
#include <cstdio>
using namespace std;
const int Max=1000100;
char S[Max],*p=S;
ifstream f("evaluare.in");
ofstream g("evaluare.out");
long termen();
long factor();
long eval();
long eval()
{
    long r = termen();
    while ( *p=='+' || *p=='-' ) {
        switch ( *p ) {
            case '+':
                ++p;                        // trecem peste semnul "+"
                r += termen();
                break;
            case '-':
                ++p;                        // trecem peste semnul "-"
                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 == '(' ) {                      // avem o subexpresie
        ++p;                                // trecem peste '('
        r = eval();
        ++p;                                // trecem peste ')'
    } else {
        while ( *p>='0' && *p<='9' )  {       // avem un numar
            r = r*10 + *p - '0';
            ++p;
        }
    }
    return r;
}
int main()
{
    fgets(S, Max, fopen("evaluare.in", "r"));
    fprintf(fopen("evaluare.out", "w"), "%ld\n", eval());
}