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copied!<p>Just for fun - Delphi code. 'shl' is left shift (<<), strings are one-based. Borders are added around the matrix as sentinels to simplify checks.</p> <p>Some additional comments: I use 6x6 matrix - 4x4 core with digits, and one-cell width outer border. 36 bits of Int64 are used as sentinels. Bit value of 1 denotes border or visited cell. Procedure StartTravel initiates path finding from some starting cell of core. Path finding goes like DFS (deep-first search), but interrupts when path length becomes 5.</p> <pre><code>const Directions: array[0..3] of Integer = (-1, -6, 1, 6); var Digits: string; Mask: Int64; i, j: Integer; procedure Travel(AFrom: Integer; Visited: Int64; Path: string); var i, Dir: Integer; NewMask: Int64; begin if Length(Path) = 5 then PrintOut(Path) else for i := 0 to 3 do begin Dir := Directions[i]; NewMask := 1 shl (AFrom + Dir); if (Visited and NewMask) = 0 then Travel(AFrom + Dir, Visited or NewMask, Path + Digits[AFrom + Dir + 1]); end; end; procedure Init; var i: Integer; begin Digits := '-------0123--7654--89AB--FEDC-------'; Mask := 0; for i := 1 to Length(Digits) do if Digits[i] = '-' then Mask := Mask or (1 shl (i - 1)); end; procedure StartTravel(Row, Col: Integer); var APos: Integer; begin APos := Row * 6 + Col + 7; Travel(APos, Mask or (1 shl APos), Digits[APos + 1]); end; begin Init; for i := 0 to 3 do for j := 0 to 3 do StartTravel(i, j); 432 combinations: 01234 01256 01254 0125A 01678 01652 01654 0165A 01698 0169A 0169E 07612 07652 .... CBADE CB456 CB452 CB45A CB432 </code></pre>

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