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OPTIONS(/E/C/-A/-Q/-I/-D);
COMMENT Procedure SORTTD will sort the contents
of the TEXT array in DESCENDING order.
Author: Algorithm 271 CACM 11-65, 5-66.
Modified by: Mats Ohlin, FOA 1, S-104 50 STOCKHOM 80, SWEDEN.
Date: 75-09-19
;
PROCEDURE sortTD (arr,n);
TEXT ARRAY arr;   INTEGER n;
BEGIN   INTEGER i,k,q,m,p;   TEXT t,x;
INTEGER ARRAY ut,lz [1:Ln(Abs(n)+2)/0.69314718];

OPTIONS(/A);
IF arr[1] < arr[n] THEN
BEGIN
t:- arr[1];
OPTIONS(/-A);   arr[1]:- arr[n];   arr[n]:- t
END test and swap;

i:= m := 1;
WHILE m > 0 DO
BEGIN
IF n-i > 1 THEN
BEGIN
p:= (n+i)//2;    t:- arr[p];
arr[p]:- arr[i];   q:= n;   k:= i;
FOR k:= k+1 WHILE k <= q DO
BEGIN
IF arr[k] < t THEN
BEGIN
WHILE q >= k DO
BEGIN
IF arr[q] > t THEN
BEGIN
x:- arr[k];   arr[k]:- arr[q];
arr[q]:- x;   q:= q-1;
GO TO l;
END;
q:= q-1;
END Q;
END;
l:
END K;
arr[i]:- arr[q];
arr[q]:- t;
IF 2*q>i+n THEN
BEGIN
lz[m]:= i;   ut[m]:= q-1;   i:= q+1;
END
ELSE
BEGIN
lz[m]:= q+1;   ut[m]:= n;   n:= q-1;
END;
m:= m+1;
END
ELSE
BEGIN
IF (IF i < n THEN arr[i] < arr[n] ELSE FALSE) THEN
BEGIN
x:- arr[i];   arr[i]:- arr[n];   arr[n]:- x
END;
m:= m-1;
IF m > 0 THEN
BEGIN   i:= lz[m];   n:= ut[m]   END;
END
END m > 0 loop;
END SORTTEXT IN DESCENDING ORDER;