56 lines
908 B
Modula-2
56 lines
908 B
Modula-2
MODULE queen;
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FROM InOut IMPORT WriteString, WriteLn;
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TYPE row = ARRAY[1..8] OF INTEGER;
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VAR maxpos: INTEGER;
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d: row;
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PROCEDURE free(i,j: INTEGER): BOOLEAN;
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VAR k: INTEGER;
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BEGIN
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FOR k := 1 TO i-1 DO
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IF (d[k]=j) OR (j-d[k]=i-k) OR (d[k]-j=i-k) THEN
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RETURN FALSE;
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END;
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END;
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RETURN TRUE;
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END free;
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PROCEDURE print;
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VAR i,j: INTEGER;
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BEGIN
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FOR j := maxpos TO 1 BY -1 DO
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FOR i := 1 TO maxpos DO
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IF d[i] = j THEN
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WriteString("D ");
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ELSE
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WriteString(". ");
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END;
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END;
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WriteLn;
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END;
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WriteLn;
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END print;
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PROCEDURE queen(k: INTEGER);
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VAR i: INTEGER;
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BEGIN
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IF k = maxpos THEN
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FOR i := 1 TO maxpos DO
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IF free(k,i) THEN
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d[k] := i;
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print();
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END;
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END;
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ELSE
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FOR i := 1 TO maxpos DO
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IF free(k,i) THEN
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d[k] := i;
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queen(k+1);
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END;
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END;
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END;
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END queen;
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BEGIN
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maxpos := 8;
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queen(1);
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END queen.
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