Cod sursa(job #3334795)

Utilizator bdav_Botea David-Alexandru bdav_ Data 19 ianuarie 2026 21:34:19
Problema Evaluarea unei expresii Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.8 kb
#include <fstream>
#include <stack>
#include <cstring>
#include <cmath>

using namespace std;

ifstream fin("input.txt");
ofstream fout("output.txt");

char s[100010];
int n, p = 0;

stack<char> op;
stack<long long> nr;

long long eval(long long x, long long y, char semn) {
    switch(semn) {
        case '+': return x+y;
        case '-': return x-y;
        case '*': return x*y;
        case '/': return x/y;
        case '^': return pow(x,y);
    }
}

long long nextnum() {
    long long numar = 0;
    while(s[p] >= '0' && s[p] <= '9')
        numar = numar*10 + (s[p++]-'0');
    return numar;
}

int prioritate(char s1, char s2) {
    if(s1 == '(')
        return 1;
    if((s1 == '-' || s1 == '+') && (s2 == '*' || s2 == '/' || s2 == '^'))
        return 1;
    if((s1 == '*' || s1 == '/') && s2 == '^')
        return 1;

    return 0;
}

void fill_op_nr() {
    int n = strlen(s);
    while(p < n) {
        switch(s[p]) {
            case '(': {
                op.push(s[p++]);
                break;
            }
            case ')': {
                while(op.top() != '(') {
                    long long v2 = nr.top();
                    nr.pop();
                    long long v1 = nr.top();
                    nr.pop();
                    char semn = op.top();
                    op.pop();
                    nr.push(eval(v1, v2, semn));
                   // fout << semn << ' ';
                }
                op.pop();
                p++;
                break;
            }
            case '+':
            case '-':
            case '*':
            case '/':
            case '^': {
                if(op.empty() || prioritate(op.top(), s[p]) == 1) {
                    op.push(s[p++]);
                }
                else {
                    do {
                        long long v2 = nr.top();
                        nr.pop();
                        long long v1 = nr.top();
                        nr.pop();
                        char semn = op.top();
                        op.pop();
                        nr.push(eval(v1, v2, semn));
                        //fout << semn << ' ';
                    } while(!op.empty() && prioritate(op.top(), s[p]) == 0);
                }
                break;
            }
            default:
                nr.push(nextnum());
                //fout << nr.top() << ' ';
        }
    }

    while(!op.empty()) {
        long long v2 = nr.top();
        nr.pop();
        long long v1 = nr.top();
        nr.pop();
        char semn = op.top();
        op.pop();
        nr.push(eval(v1, v2, semn));
        //fout << semn << ' ';
    }
}

int main() {
    fin.getline(s, 100010);
    n = strlen(s);
    fill_op_nr();
    fout << nr.top();
    return 0;
}