Selectivo 2 - P4

#include <iostream>
#include <vector>

using namespace std;

string expr;

int eval(int l, int r){
    vector<int> v,op;

    for(int i = l,k = 0,neg = 0,s = -1;i <= r;++i){
        if(expr[i] == '('){
            ++k;

            if(k == 1) s = i;
        }else if(expr[i] == ')'){
            --k;

            if(k == 0){
                v.push_back(neg ^ eval(s + 1,i - 1));
                neg = 0;
            }
        }else if(k == 0){
            if(expr[i] == '!'){
                int e = i;

                while(expr[e] == '!') ++e;
                if((e - i) & 1) neg = 1;

                if(expr[e] != '('){
                    if(expr[e] == 'V') v.push_back(neg ^ 1);
                    else v.push_back(neg);

                    neg = 0;
                }else --e;

                i = e;
            }else if(expr[i] == '&') op.push_back(1);
            else if(expr[i] == '|') op.push_back(0);
            else if(expr[i] == 'V') v.push_back(1);
            else if(expr[i] == 'F') v.push_back(0);
        }
    }

    int ret = 0,n = v.size();

    for(int i = 0;i < n;){
        int aux = v[i];
        int e = i + 1;

        while(e < n && op[e - 1] == 1){
            aux &= v[e];
            ++e;
        }

        ret |= aux;
        i = e;
    }

    return ret;
}

int main(){
    ios::sync_with_stdio(0);

    string line;
    int tc = 1;

    while(getline(cin,line)){
        int L = line.size();
        expr.clear();

        for(int i = 0;i < L;++i)
            if(line[i] != ' ')
                expr += line[i];

        if(expr.empty()) break;

        int ret = eval(0,expr.size() - 1);

        cout << "Expression " << tc++ << ": " << (ret? 'V' : 'F') << '\n';
    }

    return 0;
}