Cod sursa(job #1380196)

Utilizator Vali_DeaconuVali Deaconu Vali_Deaconu Data 6 martie 2015 23:14:06
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.2 kb
#include <cstdio>

FILE *fin, *fout;

const long MAX = 100010;
char S[MAX], *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() {
    fin = fopen("evaluare.in", "r");
    fout = fopen("evaluare.out", "w");
    fscanf (fin, "%s", S);
    fprintf(fout, "%ld\n", eval());
    return 0;
}