Cod sursa(job #2129196)

Utilizator PostMaloneLiurca Daniel PostMalone Data 12 februarie 2018 16:48:50
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.22 kb
#include <iostream>
#include <fstream>
 
using namespace std; 
 
ifstream input("evaluare.in"); 
ofstream output("evaluare.out"); 

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() { 
    input >> S;
    output << eval();  
    return 0;
}