mastermind.cpp in c++11

mastermind.cpp

#include <algorithm>
#include <iostream>
#include <map>

using namespace std;

/**
 * @brief repeat helper.
 */
template <typename F>
void repeat(unsigned n, F f)
{
    while(n--) f();
}

/**
 * @brief generate random sequence from specified list.
 *
 * @param xs a list of unique elements.
 * @param n number of elements exptected.
 *
 * @return a random list.
 */
template <typename T>
vector<T> generate_random_nseq(const vector<T>& xs, unsigned n)
{
    vector<T> vs;

    srand(time(NULL));
    repeat(n, [&vs, &xs](){
        vs.push_back(xs[rand() % xs.size()]);
    });

    return vs;
}

/**
 * helper structure for guess check. 
 */
typedef struct {
    unsigned pos_matched;   /* number of position matched */
    unsigned ele_matched;   /* number of element matched */
} match_result;

/**
 * @brief check matched result.
 *
 * @param rs real sequence value.
 * @param gs guessed sequence value.
 *
 * @return
 */
template <typename T>
match_result check_guess(const vector<T>& rs, const vector<T>& gs)
{
    match_result rst = {0, 0};

    // count occurrences of same position
    typename vector<T>::const_iterator i1, i2;

    for ( i1  = rs.begin(), i2 = gs.begin();
         i1 != rs.end() && i2 != gs.end();
         ++i1, ++i2) {
        if ((*i1) == (*i2)) rst.pos_matched += 1;
    }

    // count occurrences of same values.
    map<T, int> rs_m, gs_m;

    for(auto const & x : rs) { ++rs_m[x];}
    for(auto const & x : gs) { ++gs_m[x];}
    for(auto im : rs_m) {
        rst.ele_matched += min(im.second, gs_m[im.first]);
    }

    return rst;
}

const vector<char> COLORS = {'B', 'G', 'R'};
const unsigned NUM_ELEMENTS = 3;

int main()
{
    vector<char> vcomb = generate_random_nseq (COLORS, NUM_ELEMENTS);

    while(1)
    {
        // get guess
        string guess;

        cout << " - your guess --> ";
        cin >> guess;

        // string -> vector
        vector<char> vguess(guess.begin(), guess.end());
        if (vguess.size() != NUM_ELEMENTS) {
            cout << "Guess must be " << NUM_ELEMENTS << " elements" << endl;
            continue;
        }
        // todo: check if all elements valid.

        // check (vector, vector)
        match_result rst = check_guess(vcomb, vguess);
        cout << "Positon matched: " << rst.pos_matched
             << ", Value matched: " << rst.ele_matched << endl;
        if (rst.pos_matched == vcomb.size())
            break;
    }

    cout << " - solved!" << endl;
}