算法问题
declare
type t_matrix is table of number index by binary_integer;
v_helix t_matrix;
i number;
j number;
direction pls_integer; -- right:0, up:1, left:2, down:3
M number;
N number;
-- 模拟2维数组 begin
function new_matrix (rows integer, cols integer) return t_matrix is
v_result t_matrix;
begin
v_result(0):=cols;
for i in 1 .. rows*cols loop
v_result(i) := null;
end loop;
return v_result;
end;
procedure set_val(p_matrix in out t_matrix, i integer, j integer, val number) is
begin
p_matrix( (i-1)* p_matrix(0) +j ) := val;
end;
function get_val(p_matrix t_matrix, i integer, j integer) return number is
begin
return p_matrix( (i-1)* p_matrix(0) +j );
end;
procedure print_matrix(m t_matrix) is
i integer;
j integer;
begin
for i in 1 .. m.count/m(0) loop
for j in 1 .. m(0) loop
dbms_output.put(to_char(m((i-1)*m(0)+j),'9999990'));
end loop;
dbms_output.new_line;
end loop;
end;
-- 模拟2维数组 end
--寻找"下一个位置"
function go_next
(
p_helix in out t_matrix,
p_i in out number,
p_j in out number,
p_dir in out pls_integer,
p_altdir char
) return boolean is
dir_offset constant varchar2(16) := '+0+1-1+0+0-1+1+0'; -- i,j offset in each direction
ii number;
jj number;
times pls_integer := 0;
begin
loop
ii := p_i + substr(dir_offset, p_dir * 4 + 1, 2);
jj := p_j + substr(dir_offset, p_dir * 4 + 2 + 1, 2);
times := times + 1;
exit when(ii between 1 and p_helix.count/p_helix(0)
and jj between 1 and p_helix(0)
and get_val(p_helix,ii,jj) is null);
if times >= 4 then
return false;
end if;
if p_altdir = 'L' then -- turn left
p_dir := mod(p_dir + 1, 4);
elsif p_altdir = 'R' then -- turn right
p_dir := mod(p_dir + 3, 4);
end if;
end loop;
p_i := ii;
p_j := jj;
return true;
end;
--主程序
begin
M := 4;
N := 5;
v_helix := new_matrix(M, N);
i := 1;
j := 1;
direction := 3;
for x in 1 .. M * N loop
set_val(v_helix, i, j, x);
exit when not go_next(v_helix, i, j, direction, 'L');
end loop;
print_matrix(v_helix);
--已经完成任务，以下可以叫做画蛇添足：）
dbms_output.new_line;
v_helix := new_matrix(M, N);
i := 1;
j := 1;
direction := 0;
for x in 1 .. M * N loop
set_val(v_helix, i, j, x);
exit when not go_next(v_helix, i, j, direction, 'R');
end loop;
print_matrix(v_helix);
dbms_output.new_line;
v_helix := new_matrix(M, N);
i := 1;
j := 1;
direction := 3;
for x in 1 .. M * N loop
set_val(v_helix, i, j, M*N-x+1);
exit when not go_next(v_helix, i, j, direction, 'L');
end loop;
print_matrix(v_helix);
dbms_output.new_line;
v_helix := new_matrix(M, N);
i := 1;
j := 1;
direction := 0;
for x in 1 .. M * N loop
set_val(v_helix, i, j, M*N-x+1);
exit when not go_next(v_helix, i, j, direction, 'R');
end loop;
print_matrix(v_helix);
end;
1 14 13 12 11
2 15 20 19 10
3 16 17 18 9
4 5 6 7 8
1 2 3 4 5
14 15 16 17 6
13 20 19 18 7
12 11 10 9 8
20 7 8 9 10
19 6 1 2 11
18 5 4 3 12
17 16 15 14 13
20 19 18 17 16
7 6 5 4 15
8 1 2 3 14
9 10 11 12 13
---------------
declare
procedure draw_helix ( M number, N number, init_i integer, init_j integer, init_dir integer, screw_dir char, asc_order boolean := true) is
type t_matrix is table of number index by binary_integer;
v_helix t_matrix;
element number;
i integer := init_i;
j integer := init_j;
direction integer := init_dir; -- right:0, up:1, left:2, down:3
-- 模拟2维数组 begin
function new_matrix( rows integer, cols integer ) return t_matrix is
v_result t_matrix;
begin
v_result(0) := cols;
for i in 1 .. rows * cols loop
v_result(i) := null;
end loop;
return v_result;
end;
procedure set_val (p_matrix in out t_matrix, i integer, j integer, val number ) is
begin
p_matrix((i - 1) * p_matrix(0) + j) := val;
end;
function get_val ( p_matrix t_matrix, i integer, j integer ) return number is
begin
return p_matrix((i - 1) * p_matrix(0) + j);
end;
procedure print_matrix(m t_matrix) is
i integer;
j integer;
begin
for i in 1 .. m.count / m(0) loop
for j in 1 .. m(0) loop
dbms_output.put( lpad(nvl(to_char(m((i - 1) * m(0) + j)), ' '), 8, ' ') );
end loop;
dbms_output.new_line;
end loop;
end;
-- 模拟2维数组 end
--寻找"下一个位置"
function go_next (p_helix in t_matrix, p_i in out number, p_j in out number, p_dir in out pls_integer, p_altdir char) return boolean is
dir_offset constant varchar2(16) := '+0+1-1+0+0-1+1+0'; -- i,j offset in each direction
ii number;
jj number;
times pls_integer := 0;
begin
loop
ii := p_i + substr(dir_offset, p_dir * 4 + 1, 2);
jj := p_j + substr(dir_offset, p_dir * 4 + 2 + 1, 2);
times := times + 1;
exit when(ii between 1 and p_helix.count / p_helix(0) and jj between 1 and p_helix(0) and
get_val(p_helix, ii, jj) is null);
if times >= 4 then
return false;
end if;
if p_altdir = 'L' then
-- turn left
p_dir := mod(p_dir + 1, 4);
elsif p_altdir = 'R' then
-- turn right
p_dir := mod(p_dir + 3, 4);
end if;
end loop;
p_i := ii;
p_j := jj;
return true;
end;
--begin of draw_helix
begin
v_helix := new_matrix(M, N);
for x in 1 .. M*N loop
if asc_order then
element := x;
else
element := M*N - x + 1;
end if;
set_val(v_helix, i, j, element);
exit when not go_next(v_helix, i, j, direction, screw_dir);
end loop;
print_matrix(v_helix);
dbms_output.new_line;
end;
--begin of main
begin
draw_helix(4, 5, 1, 1, 3, 'L', true);
draw_helix(4, 5, 1, 1, 0, 'R', true);
draw_helix(4, 5, 1, 1, 3, 'L', false);
draw_helix(4, 5, 4, 5, 2, 'R', true);
draw_helix(4, 5, 1, 5, 2, 'L', true);
draw_helix(4, 5, 1, 5, 3, 'R', false);
draw_helix(4, 5, 3, 3, 3, 'R', true);
draw_helix(4, 5, 2, 3, 3, 'R', true);
end;
1 14 13 12 11
2 15 20 19 10
3 16 17 18 9
4 5 6 7 8
1 2 3 4 5
14 15 16 17 6
13 20 19 18 7
12 11 10 9 8
20 7 8 9 10
19 6 1 2 11
18 5 4 3 12
17 16 15 14 13
8 9 10 11 12
7 18 19 20 13
6 17 16 15 14
5 4 3 2 1
5 4 3 2 1
6 17 16 15 14
7 18 19 20 13
8 9 10 11 12
10 9 8 7 20
11 2 1 6 19
12 3 4 5 18
13 14 15 16 17
7 8 9 10 11
6 19 18 17 12
5 20 1 16 13
4 3 2 15 14
8 9 10 11 12
7 1 18 13
6 2 17 14
5 4 3 16 15
---
declare
procedure draw_helix ( M number, N number, init_i integer, init_j integer, init_dir integer, screw_dir char, asc_order boolean := true) is
type t_matrix is table of number index by binary_integer;
v_helix t_matrix;
element number;
i integer := init_i;
j integer := init_j;
direction integer := init_dir; -- right:0, up:1, left:2, down:3
-- 模拟2维数组 begin
function new_matrix( rows integer, cols integer ) return t_matrix is
v_result t_matrix;
begin
v_result(0) := cols;
for i in 1 .. rows * cols loop
v_result(i) := null;
end loop;
return v_result;
end;
procedure set_val (p_matrix in out t_matrix, i integer, j integer, val number ) is
begin
p_matrix((i - 1) * p_matrix(0) + j) := val;
end;
function get_val ( p_matrix t_matrix, i integer, j integer ) return number is
begin
return p_matrix((i - 1) * p_matrix(0) + j);
end;
procedure print_matrix(m t_matrix) is
i integer;
j integer;
begin
for i in 1 .. m.count / m(0) loop
for j in 1 .. m(0) loop
dbms_output.put( lpad(nvl(to_char(m((i - 1) * m(0) + j)), ' '), 8, ' ') );
end loop;
dbms_output.new_line;
end loop;
end;
-- 模拟2维数组 end
--寻找"下一个位置"
function go_next (p_helix in t_matrix, p_i in out number, p_j in out number, p_dir in out pls_integer, p_altdir char) return boolean is
--dir_offset constant varchar2(16) := '+0+1-1+0+0-1+1+0'; -- i,j offset in each direction
dir_offset constant varchar2(16) := '-1+1-1-1+1-1+1+1'; -- i,j offset in each direction
ii number;
jj number;
times pls_integer := 0;
begin
loop
ii := p_i + substr(dir_offset, p_dir * 4 + 1, 2);
jj := p_j + substr(dir_offset, p_dir * 4 + 2 + 1, 2);
times := times + 1;
exit when(ii between 1 and p_helix.count / p_helix(0) and jj between 1 and p_helix(0) and
get_val(p_helix, ii, jj) is null);
if times >= 4 then
return false;
end if;
if p_altdir = 'L' then
-- turn left
p_dir := mod(p_dir + 1, 4);
elsif p_altdir = 'R' then
-- turn right
p_dir := mod(p_dir + 3, 4);
end if;
end loop;
p_i := ii;
p_j := jj;
return true;
end;
--begin of draw_helix
begin
v_helix := new_matrix(M, N);
for x in 1 .. M*N loop
if asc_order then
element := x;
else
element := M*N - x + 1;
end if;
set_val(v_helix, i, j, element);
exit when not go_next(v_helix, i, j, direction, screw_dir);
end loop;
print_matrix(v_helix);
dbms_output.new_line;
end;
--begin of main
begin
draw_helix(9, 9, 1, 5, 3, 'R', true);
end;
1
16 2
15 17 3
14 24 18 4
13 23 25 19 5
12 22 20 6
11 21 7
10 8
9
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