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#ifndef __KTOURBOARD_H
#define __KTOURBOARD_H

#include <cmath>
#include <iomanip>
#include <iostream>
#include <vector>
#include "pos.h"

using namespace std;

class KTourBoard {
    int width, height;
    int *cells;
    Pos pos;
    public:
        KTourBoard(int, int);
        void solve();
        void setPos(Pos);
        friend ostream &operator<<(ostream &, KTourBoard &);
    private:
        Pos getNextPos();
        vector<Pos> getPossiblePosVector();
        vector<Pos> getPossiblePosVector(Pos);
        bool isAvailablePos(Pos);
        bool isValidPos(Pos);
        int pos2int(Pos);
};

KTourBoard::KTourBoard(int width, int height) {
    this->width = width;
    this->height = height;
    cells = new int[width * height];
    for (int i = 0; i < width * height; i++) {
        cells[i] = 0;
    }
}

void KTourBoard::solve() {
    int i = 1;
    cells[pos2int(pos)] = i++;

    while (i <= width * height) {
        pos = getNextPos();
        cells[pos2int(pos)] = i++;
    }
}

int KTourBoard::pos2int(Pos pos) {
    return pos.getx() + width * pos.gety();
}

bool KTourBoard::isValidPos(Pos pos) {
    return pos.getx() >= 0 && pos.gety() >= 0 && pos.getx() < width && pos.gety() < height;
}

bool KTourBoard::isAvailablePos(Pos pos) {
    return isValidPos(pos) && !cells[pos2int(pos)];
}

vector<Pos> KTourBoard::getPossiblePosVector() {
    return getPossiblePosVector(pos);
}

vector<Pos> KTourBoard::getPossiblePosVector(Pos pos) {
    vector<Pos> possible;

    if (isAvailablePos(pos + Pos(1, 2))) possible.push_back(pos + Pos(1, 2));
    if (isAvailablePos(pos + Pos(2, 1))) possible.push_back(pos + Pos(2, 1));
    if (isAvailablePos(pos + Pos(1, -2))) possible.push_back(pos + Pos(1, -2));
    if (isAvailablePos(pos + Pos(-2, 1))) possible.push_back(pos + Pos(-2, 1));
    if (isAvailablePos(pos + Pos(-1, 2))) possible.push_back(pos + Pos(-1, 2));
    if (isAvailablePos(pos + Pos(2, -1))) possible.push_back(pos + Pos(2, -1));
    if (isAvailablePos(pos + Pos(-1, -2))) possible.push_back(pos + Pos(-1, -2));
    if (isAvailablePos(pos + Pos(-2, -1))) possible.push_back(pos + Pos(-2, -1));

    return possible;
}

Pos KTourBoard::getNextPos() {
    vector<Pos> possible = getPossiblePosVector();

    Pos smallestPos;
    unsigned int smallest = 8;

    for (unsigned int i = 0; i < possible.size(); i++) {
        vector<Pos> next = getPossiblePosVector(possible[i]);
        if (next.size() < smallest) {
            smallest = next.size();
            smallestPos = possible[i];
        }
    }

    return smallestPos;
}

void KTourBoard::setPos(Pos pos) {
    this->pos = pos;
}

ostream &operator<<(ostream &stream, KTourBoard &board) {
    int i, j, width = log(board.width * board.height) / log(10) + 1;
    
    for (i = 0; i < board.height; i++) {
        for (j = 0; j < board.width; j++) {
            stream << setw(width) << board.cells[i * board.width + j] << " ";
        }

        stream << endl;
    }

    return stream;
}

#endif