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[pdp8.git] / sw / src / pascal / KNIGHT.PS
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1PROGRAM KNIGHTSTOUR(OUTPUT);
2
3CONST N = 5; NSQ = 25;
4
5VAR I,J: INTEGER;
6 Q: BOOLEAN;
7 A,B: ARRAY[1..8] OF INTEGER;
8 H: ARRAY[1..N,1..N] OF INTEGER;
9
10PROCEDURE TRY(I: INTEGER; X,Y: INTEGER; VAR Q: BOOLEAN);
11 VAR K,U,V: INTEGER; Q1: BOOLEAN;
12BEGIN K := 0;
13 REPEAT K:= K+1; Q1 := FALSE;
14 U := X + A[K]; V := Y + B[K];
15 IF (1<=U) AND (U<=N) AND (1<=V) AND (V<=N) THEN
16 IF H[U,V] = 0 THEN
17 BEGIN H[U,V] := I;
18 IF I < NSQ THEN
19 BEGIN TRY(I+1,U,V,Q1);
20 IF NOT Q1 THEN H[U,V] := 0
21 END ELSE Q1 := TRUE
22 END
23 UNTIL Q1 OR (K=8);
24 Q := Q1
25END (* TRY *);
26
27BEGIN
28 A[1] := 2; B[1] := 1;
29 A[2] := 1; B[2] := 2;
30 A[3] := -1; B[3] := 2;
31 A[4] := -2; B[4] := 1;
32 A[5] := -2; B[5] := -1;
33 A[6] := -1; B[6] := -2;
34 A[7] := 1; B[7] := -2;
35 A[8] := 1; B[8] := -1;
36
37 FOR I := 1 TO N DO
38 FOR J := 1 TO N DO H[I,J] := 0;
39 H[1,1] := 1; TRY(2,1,1,Q);
40 IF Q THEN
41 FOR I := 1 TO N DO
42 BEGIN FOR J := 1 TO N DO WRITE( H[I,J] :5);
43 WRITELN
44 END
45 ELSE WRITELN("KEINE LOESUNG!")
46END.