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class TOWER
creation full, empty
feature {NONE}
t:ARRAY[INTEGER];
top:INTEGER;
feature {NONE}
full(n:INTEGER) is
require
n >= 1
local
i:INTEGER;
do
!!t.make(1,n);
from
i := n;
until
i = 0
loop
t.put(n-i+1,i);
i := i - 1;
end;
top := n;
ensure
nb = n;
top = nb;
t.item(top) = 1
end;
empty(n:INTEGER) is
require
n >= 1
do
!!t.make(1,n);
top := 1;
ensure
nb = n;
top = 1
end;
feature {HANOI}
nb: INTEGER is
do
Result := t.upper;
end;
show_a_discus(d: INTEGER; picture: STRING) is
require
1 <= d;
d <= nb;
picture /= Void
local
nb_of_free_slots, nb_of_used_slots, i : INTEGER;
do
nb_of_used_slots := t.item(d);
nb_of_free_slots := nb - nb_of_used_slots;
from
i := nb_of_free_slots;
until
i = 0
loop
picture.extend(' ');
i := i - 1;
end;
from
i := nb_of_used_slots;
until
i = 0
loop
picture.extend('=');
i := i - 1;
end;
picture.extend('|');
from
i := nb_of_used_slots;
until
i = 0
loop
picture.extend('=');
i := i -1;
end;
from
i := nb_of_free_slots;
until
i = 0
loop
picture.extend(' ');
i := i - 1;
end;
end;
remove_discus: INTEGER is
do
debug
if t.item(top) = 0 then
std_error.put_string("Error in 'remove_discus'.%N");
crash;
end;
end;
Result := t.item(top);
t.put(0,top);
if top > 1 then
top := top - 1;
end;
ensure
top >= 1
end;
add_discus(d: INTEGER) is
do
debug
if (top = nb) then
std_error.put_string("Error in 'add_discus', %
%the tower was already full.%N")
crash;
end;
if (d > t.item(top)) then
-- std_error.put_string("Error in 'add_discus', the %
-- %discus you wanted to put is larger %
-- %than allowed.");
-- crash;
end;
end;
if t.item(top) > d then
top := top + 1;
t.put(d,top);
end;
if t.item(top) = 0 then
t.put(d,top);
end;
ensure
top <= nb
end;
end -- TOWER
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