RosettaCodeData/Task/Hailstone-sequence/PL-I/hailstone-sequence.pli

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test: proc options (main);
declare (longest, n) fixed (15);
declare flag bit (1);
declare (i, value) fixed (15);
/* Task 1: */
flag = '1'b;
put skip list ('The sequence for 27 is');
i = hailstones(27);
/* Task 2: */
flag = '0'b;
longest = 0;
do i = 1 to 99999;
if longest < hailstones(i) then
do; longest = hailstones(i); value = i; end;
end;
put skip edit (value, ' has the longest sequence of ', longest) (a);
hailstones: procedure (n) returns ( fixed (15));
declare n fixed (15) nonassignable;
declare (m, p) fixed (15);
m = n;
p = 1;
if flag then put skip list (m);
do p = 1 by 1 while (m > 1);
if iand(m, 1) = 0 then
m = m/2;
else
m = 3*m + 1;
if flag then put skip list (m);
end;
if flag then put skip list ('The hailstone sequence has length' || p);
return (p);
end hailstones;
end test;