Knight tour checking

t13e15.knightTourCheck.cpp

// t13e15.knightTourCheck.cpp
// juanfc 2023-11-23
// 

#include <iostream>
#include <array>
using namespace std;

const int N = 8;
typedef array<array<int,N>,N> TChessboard;


bool checkKnight(TChessboard t, int i=0, int j=0);

int main()
{
    TChessboard t = {{
        {{ 1, 64, 61, 42, 37, 40, 55, 52}},
        {{60, 43,  2, 63, 56, 53, 36, 39}},
        {{ 3, 62, 59, 20, 41, 38, 51, 54}},
        {{44, 19,  4, 57, 50, 21, 32, 35}},
        {{ 5, 58, 45, 18, 31, 34, 49, 22}},
        {{14, 17,  6, 25, 46, 11, 30, 33}},
        {{ 7, 26, 15, 12,  9, 28, 23, 48}},
        {{16, 13,  8, 27, 24, 47, 10, 29}},
    }};
    cout << "Chess Knight tour ";
    if (checkKnight(t)) cout << "CORRECT" << endl;
    else                cout << "INCORRECT" << endl;

    t = (TChessboard) {{
        {{ 0,  59,  38,  33,  30,  17,   8,  63}},
        {{37,  34,  31,  60,   9,  62,  29,  16}},
        {{58,   1,  36,  39,  32,  27,  18,   7}},
        {{35,  48,  41,  26,  61,  10,  15,  28}},
        {{42,  57,   2,  49,  40,  23,   6,  19}},
        {{47,  50,  45,  54,  25,  20,  11,  14}},
        {{56,  43,  52,   3,  22,  13,  24,   5}},
        {{51,  46,  55,  44,  53,   4,  21,  12}},
    }};
    cout << "Chess Knight tour ";
    if (checkKnight(t)) cout << "CORRECT" << endl;
    else                cout << "INCORRECT" << endl;

    return 0;
}


bool nextIsOk(TChessboard t, int& ii, int& jj);
bool checkKnight(TChessboard t, int i, int j)
{
    int cnt = 1;
    int cntMax = N*N;
    while ( nextIsOk(t, i, j) )
        ++cnt;
    return cnt == cntMax;
}

bool isIn(TChessboard t, int i, int j, int v);
bool nextIsOk(TChessboard t, int& ii, int& jj)
{
    int i = ii, j = jj;
    int shouldBe = t[i][j] + 1;

    if (      isIn(t, i+1, j+2, shouldBe)) { ii = i+1; jj = j+2; }
     else if (isIn(t, i-1, j+2, shouldBe)) { ii = i-1; jj = j+2; }
     else if (isIn(t, i-2, j+1, shouldBe)) { ii = i-2; jj = j+1; }
     else if (isIn(t, i-2, j-1, shouldBe)) { ii = i-2; jj = j-1; }
     else if (isIn(t, i-1, j-2, shouldBe)) { ii = i-1; jj = j-2; }
     else if (isIn(t, i+1, j-2, shouldBe)) { ii = i+1; jj = j-2; }
     else if (isIn(t, i+2, j-1, shouldBe)) { ii = i+2; jj = j-1; }
     else if (isIn(t, i+2, j+1, shouldBe)) { ii = i+2; jj = j+1; }
    return ii != i;
}

bool isIn(TChessboard t, int i, int j, int v)
{
    return i>=0 and i<N and j>=0 and j<N and t[i][j] == v;
}