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///////////////////////////////////////////////////////////////////////////////
// Lisaac Example //
// //
// LSIIT - ULP - CNRS - INRIA - FRANCE //
// //
// This program is free software: you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation, either version 3 of the License, or //
// (at your option) any later version. //
// //
// This program is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
// //
// http://isaacproject.u-strasbg.fr/ //
///////////////////////////////////////////////////////////////////////////////
Section Header
+ name := PYRAMID;
- author := "Sonntag Benoit (bsonntag@loria.fr)";
- comment :=
" Solving the problem of the Pyramid for small pyramid only. \
\ This program uses the back-tracking method. \
\ Its goal is to try to fill a pyramid by making a substraction \
\ between two succesive columns and to take its absolute value. \
\ The result is put on the next line. \
\ Example: \
\ 6 14 15 3 13 \
\ 8 1 12 10 \
\ 7 11 2 \
\ 4 9 \
\ 5 \
\ See also pyramid2, which run faster than this first solution.";
Section Inherit
- parent_object:OBJECT := OBJECT;
Section Private
+ size:INTEGER;
- max:INTEGER <- (size * (size + 1)) / 2;
- belongs_to nb:INTEGER :BOOLEAN <-
( + i:INTEGER;
+ found:BOOLEAN;
? { nb.in_range 1 to max};
i := 1;
{(i > max) | found}.until_do {
found := (nb = elem.item i);
i := i + 1;
};
found
);
- propagate (col,val_column_1:INTEGER) :BOOLEAN <-
( + stop:BOOLEAN;
+ line:INTEGER;
+ val:INTEGER;
+ result:BOOLEAN;
? { val_column_1.in_range 1 to max};
? { col.in_range 1 to size};
(belongs_to val_column_1).if {
result := FALSE ;
} else {
elem.put val_column_1 to (indice (1,col));
line := 1;
val := val_column_1;
result := TRUE;
{stop}.until_do {
line := line + 1;
(line > col).if {
stop := TRUE;
} else {
val := val - elem.item (indice ((line-1),(col-line+1)));
val := val.abs;
(belongs_to val).if {
clear_column col;
stop := TRUE;
result := FALSE;
} else {
elem.put val to (indice (line,(col-line+1)));
};
};
};
};
result
);
- fill_up col:INTEGER :BOOLEAN <-
( + stop,result:BOOLEAN;
+ nb:INTEGER;
? { col >= 1};
(col > size).if {
result := TRUE;
} else {
nb := max;
{stop}.until_do {
(belongs_to nb).if {
nb := nb - 1;
stop := (nb = 0);
}.elseif {propagate (col,nb)} then {
(fill_up (col + 1)).if {
stop := TRUE;
} else {
clear_column col;
nb := nb - 1;
stop := (nb = 0);
};
} else {
nb := nb - 1;
stop := (nb = 0);
};
};
result := (nb > 0);
};
result
);
+ elem:ARRAY[INTEGER];
+ case_empty:INTEGER; // = 0 by default
+ biggest_one:INTEGER := 10;
- indice (line,col:INTEGER) :INTEGER <-
( + l:INTEGER;
+ result:INTEGER;
? {line.in_range 1 to size};
? {col.in_range 1 to size};
l:= size - line + 1;
result := max - ((l * (l + 1)) / 2) + col;
? {result.in_range 1 to max};
result
);
- clear_column col:INTEGER <-
(
? {col.in_range 1 to size};
1.to col do { line:INTEGER;
elem.put case_empty to (indice (line,(col-line+1)));
};
); // clear_column
- print <-
( + line,col:INTEGER;
line := 1;
col := 1;
1.to max do { nb:INTEGER;
(col = 1).if {
'\n'.print;
};
elem.item (indice (line,col)).print;
' '.print;
(col = size - line + 1).if {
col := 1 ;
line := line + 1 ;
} else {
col := col + 1;
};
};
'\n'.print;
);
Section Public
- main <-
(
// Read argument.
(COMMAND_LINE.upper = 0).if {
"Want to compute a small pyramid ?\n\
\Enter a small number (> 1): ".print;
IO.read_integer;
size := IO.last_integer;
} else {
size := COMMAND_LINE.item 1.to_integer;
};
(size <= 1).if {
"You feel sick ?\n".print;
}.elseif {size > biggest_one} then {
"Value too big for this method.\n".print;
} else {
elem := ARRAY[INTEGER].create 1 to max;
(fill_up 1).if {
"Full pyramid:\n".print;
print;
} else {
"Unable to fill_up such one.\n".print;
};
};
);
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