COMMENT
This routine is used in more then one place, and is essentially a
template that can by used for many different types, eg INT, LONG INT...
USAGE
MODE SORTSTRUCT = INT, LONG INT, STRUCT(STRING name, addr) etc
OP < = (SORTSTRUCT a,b)BOOL: ~;
PR READ "prelude/sort.a68" PR;
[3]SORTSTRUCT list := (a,b,c);
print((in place shell sort(list), new line))
END COMMENT
PROC in place shell sort = (REF FLEX []SORTSTRUCT seq)REF[]SORTSTRUCT:(
INT inc := ( UPB seq + LWB seq + 1 ) OVER 2;
WHILE inc NE 0 DO
FOR index FROM LWB seq TO UPB seq DO
INT i := index;
SORTSTRUCT el = seq[i];
WHILE ( i - LWB seq >= inc | NOT(seq[i - inc] < el) | FALSE ) DO
seq[i] := seq[i - inc];
i -:= inc
OD;
seq[i] := el
OD;
inc := IF inc = 2 THEN 1 ELSE ENTIER(inc * 5 / 11) FI
OD;
seq
);
PROC in place shell sort reverse = (REF FLEX []SORTSTRUCT seq)REF[]SORTSTRUCT:(
INT inc := ( UPB seq + LWB seq + 1 ) OVER 2;
WHILE inc NE 0 DO
FOR index FROM LWB seq TO UPB seq DO
INT i := index;
SORTSTRUCT el = seq[i];
WHILE ( i - LWB seq >= inc | seq[i - inc] < el | FALSE ) DO
seq[i] := seq[i - inc];
i -:= inc
OD;
seq[i] := el
OD;
inc := IF inc = 2 THEN 1 ELSE ENTIER(inc * 5 / 11) FI
OD;
seq
);
SKIP
This is a template. There are many others. See Category:RCTemplates for a complete list of templates.
