Cod sursa(job #1977573)

Utilizator MaligMamaliga cu smantana Malig Data 5 mai 2017 15:44:06
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.12 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>

using namespace std;
ifstream in("evaluare.in");
ofstream out("evaluare.out");

#define pb push_back
#define ll long long
const int NMax = 1e5 + 5;
const int inf = 1e5 + 5;

char str[NMax],*p = str;

int eval();
int termen();
int factor();

int main()
{
    in>>(str);
    out<<eval()<<'\n';

    in.close();out.close();
    return 0;
}

int eval() {
    int ans = termen();
    while (*p == '+' || *p == '-') {
        switch (*p++) {
        case '+': ans += termen(); break;
        case '-': ans -= termen(); break;
        }
    }
    return ans;
}

int termen() {
    int ans = factor();
    while (*p == '*' || *p == '/') {
        switch (*p++) {
        case '*': ans *= factor(); break;
        case '/': ans /= factor(); break;
        }
    }
    return ans;
}

int factor() {
    int ans = 0;
    if (*p == '(') {
        ++p;
        ans = eval();
        ++p;
    }
    else {
        while ('0' <= *p && *p <= '9') {
            ans = ans * 10 + *p++ - '0';
        }
    }
    return ans;
}