ErasingCharacters.cpp

#include <bits/stdc++.h>
using namespace std;

class ErasingCharacters {
public:
    string simulate(string s) {
        string ret;
        stack<char> ss;
        int n = s.size();
        for (int i = 0; i < n; i++) {
            if (ss.size() != 0 && ss.top() == s[i]) {
                ss.pop();
            } else {
                ss.push(s[i]);
            }
        }
        while (ss.size()) {
            ret.push_back(ss.top());
            ss.pop();
        }
        reverse(ret.begin(), ret.end());
        return ret;
    }

    // BEGIN CUT HERE
public:
    void run_test(int Case) {
        if ((Case == -1) || (Case == 0)) test_case_0();
        if ((Case == -1) || (Case == 1)) test_case_1();
        if ((Case == -1) || (Case == 2)) test_case_2();
        if ((Case == -1) || (Case == 3)) test_case_3();
        if ((Case == -1) || (Case == 4)) test_case_4();
    }

private:
    template <typename T>
    string print_array(const vector<T>& V) {
        ostringstream os;
        os << "{ ";
        for (typename vector<T>::const_iterator iter = V.begin(); iter != V.end(); ++iter) os << '\"' << *iter << "\",";
        os << " }";
        return os.str();
    }
    void verify_case(int Case, const string& Expected, const string& Received) {
        cerr << "Test Case #" << Case << "...";
        if (Expected == Received)
            cerr << "PASSED" << endl;
        else {
            cerr << "FAILED" << endl;
            cerr << "\tExpected: \"" << Expected << '\"' << endl;
            cerr << "\tReceived: \"" << Received << '\"' << endl;
        }
    }
    void test_case_0() {
        string Arg0 = "cieeilll";
        string Arg1 = "cl";
        verify_case(0, Arg1, simulate(Arg0));
    }
    void test_case_1() {
        string Arg0 = "topcoder";
        string Arg1 = "topcoder";
        verify_case(1, Arg1, simulate(Arg0));
    }
    void test_case_2() {
        string Arg0 = "abcdefghijklmnopqrstuvwxyyxwvutsrqponmlkjihgfedcba";
        string Arg1 = "";
        verify_case(2, Arg1, simulate(Arg0));
    }
    void test_case_3() {
        string Arg0 = "bacaabaccbaaccabbcabbacabcbba";
        string Arg1 = "bacbaca";
        verify_case(3, Arg1, simulate(Arg0));
    }
    void test_case_4() {
        string Arg0 = "eel";
        string Arg1 = "l";
        verify_case(4, Arg1, simulate(Arg0));
    }

    // END CUT HERE
};

// BEGIN CUT HERE
int main() {
    ErasingCharacters ___test;
    ___test.run_test(-1);
    int gbase;
    cin >> gbase;  // erase this line if you are not using dev-cpp! :)
    return 0;
}
// END CUT HERE