Cod sursa(job #2700907)

Utilizator lucamLuca Mazilescu lucam Data 29 ianuarie 2021 11:57:10
Problema Evaluarea unei expresii Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.17 kb
#include <fstream>
#include <cstring>
#include <cctype>
#include <fstream>

constexpr int N = 100000;
char s[N + 1];
char *p = s;

int expresie();
int termen();
int factor();

int expresie() {
    int sum = termen();
    while (*p && strchr("+-", *p)) {
        ++p;
        if (p[-1] == '+') {
            sum += termen();
        }
        else {
            sum -= termen();
        }
    }
    return sum;
}

int termen() {
    int prod = factor();
    while (*p && strchr("/*", *p)) {
        ++p;
        if (p[-1] == '*') {
            prod *= factor();
        }
        else {
            prod /= factor();
        }
    }
    return prod;
}

int factor() {
    int val = 0;
    int sign = 1;
    while (*p == '-') {
        sign = -sign;
        ++p;
    }
    if (*p == '(') {
        ++p;
        val = expresie();
        ++p;
        return sign * val;
    }
    while (isdigit(*p)) {
        val = val * 10 + *p - '0';
        ++p;
    }
    return sign * val;
}

int main() {
    std::ifstream in("evaluare.in");
    std::ofstream out("evaluare.out");
    in.getline(s, sizeof s);
    out << expresie() << '\n';
}