Kinx Algorithm-Eight Queens

Introduction

** "Looks like JavaScript, brain (contents) is Ruby, (stability is AC / DC)" ** Scripting language Kinx ). "Program = algorithm + data structure". Introducing an implementation example of the algorithm.

The original story is "The latest algorithm encyclopedia in C language (even after 30 years)". This time it's Eight Queens (generally N Queens).

Reference
First motivation ... Script language KINX (introduction)
All links to individual articles are collected here.
Repository ... https://github.com/Kray-G/kinx
We are waiting for Pull Request etc.

There are quite a few such things in the latest algorithm encyclopedia. It's like a puzzle.

Eight queens also made samples in the early days of Kinx and used them to see if they could come up with 92 solutions.

Eight queens

https://ja.wikipedia.org/wiki/%E3%82%A8%E3%82%A4%E3%83%88%E3%83%BB%E3%82%AF%E3%82%A4%E3%83%BC%E3%83%B3

From Wikipedia

Eight queens is the name of a puzzle that uses chess boards and pieces. Place eight queens on the chess board. At this time, no piece must be in a position where it can be taken by another piece.

N Queens is an extension of these 8 to ** n **.

Source code

var a = [], b = [], c = [], x = [];
var solution = 0;

function found(n) {
    System.print("\nSolution %d\n" % ++solution);
    for (var i = 0; i < n; i++) {
        for (var j = 0; j < n; j++)
            if (x[i] == j) System.print(" Q");
            else           System.print(" .");
        System.print("\n");
    }
}

function test(i, n) {
    for (var j = 0; j < n; j++)
        if (a[j] && b[i + j] && c[i - j + n - 1]) {
            x[i] = j;
            if (i < n - 1) {
                a[j] = b[i + j] = c[i - j + n - 1] = 0;
                test(i + 1, n);
                a[j] = b[i + j] = c[i - j + n - 1] = 1;
            } else found(n);
        }
}

function nqueen(n) {
    for (var i = 0; i < n; i++)         a[i] = 1;
    for (var i = 0; i < 2 * n - 1; i++) b[i] = 1;
    for (var i = 0; i < 2 * n - 1; i++) c[i] = 1;
    test(0, n);
}

nqueen(8);

result

Solution 1
 Q . . . . . . .
 . . . . Q . . .
 . . . . . . . Q
 . . . . . Q . .
 . . Q . . . . .
 . . . . . . Q .
 . Q . . . . . .
 . . . Q . . . .

Solution 2
 Q . . . . . . .
 . . . . . Q . .
 . . . . . . . Q
 . . Q . . . . .
 . . . . . . Q .
 . . . Q . . . .
 . Q . . . . . .
 . . . . Q . . .

Solution 3
 Q . . . . . . .
 . . . . . . Q .
 . . . Q . . . .
 . . . . . Q . .
 . . . . . . . Q
 . Q . . . . . .
 . . . . Q . . .
 . . Q . . . . .

...(abridgement)

Solution 92
 . . . . . . . Q
 . . . Q . . . .
 Q . . . . . . .
 . . Q . . . . .
 . . . . . Q . .
 . Q . . . . . .
 . . . . . . Q .
 . . . . Q . . .

in conclusion

This is also almost the same as the C language version.

I remember those days when things like this worked, and I felt like I was moving forward with a "feeling of success." After all, it was the first step to be able to do various things when the access of array elements and the increment / decrement became proper.

See you next time.