Cod sursa(job #2371156)

Utilizator caesar2001Stoica Alexandru caesar2001 Data 6 martie 2019 16:17:49
Problema Evaluarea unei expresii Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.3 kb
#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <utility>
#include <cmath>
#include <string>
#include <cstring>
#include <set>
#include <queue>
#include <map>
#include <stack>
#define ll long long

using namespace std;

ifstream in("evaluare.in");
ofstream out("evaluare.out");

int getresult(int a, int b, char c) {
    if(c == '+')
        return a + b;
    if(c == '-')
        return a - b;
    if(c == '*')
        return a * b;
    if(c == '/')
        return a / b;
}

bool isoperator(char c) {
    if(c == '+' || c == '-' || c == '*' || c == '/')
        return 1;
    return 0;
}

int priority(char c) {
    if(c == '+' || c == '-')
        return 1;
    if(c == '/' || c == '*')
        return 2;
}

int main() {

    string s;
    in >> s;

    stack<char> op;
    stack<int> values;
    int i = 0;
    while(i < s.size()) {
        if(s[i] == '(') {
            op.push(s[i]);
            i ++;
        } else if(s[i] == ')') {
            while(op.top() != '(') {
                int a = values.top();
                values.pop();
                int b = values.top();
                values.pop();

                a = getresult(b, a, op.top());
                values.push(a);
                op.pop();
            }
            op.pop();
            i ++;

        } else if(isoperator(s[i])) {
            while(op.size() && isoperator(op.top()) && priority(s[i]) <= priority(op.top())) {
                int a = values.top();
                values.pop();
                int b = values.top();
                values.pop();

                a = getresult(b, a, op.top());
                values.push(a);
                op.pop();
            }

            op.push(s[i]);
            i ++;

        } else {
            int nr = 0;
            while(i < s.size() && isdigit(s[i])) {
                nr = nr * 10;
                nr += (s[i] - '0');
                i ++;
            }
            values.push(nr);
        }
    }

    while(op.size()) {
        int a = values.top();
        values.pop();
        int b = values.top();
        values.pop();

        a = getresult(b, a, op.top());
        values.push(a);
        op.pop();
    }

    out << values.top();

    return 0;
}