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NPR Sunday puzzle

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use v6;
my $set_abcdef = set 'abcdef'.comb(/./);
sub npr_word($word) {
# too slow
$word.chars == 8 and $set_abcdef (<=) (set $word.comb(/./));
}
sub MAIN($dict_file='/usr/share/dict/british-english') {
my @words = slurp($dict_file).words;
say grep { npr_word($_) }, @words;
}
view raw npr.pl hosted with ❤ by GitHub
Unknown's avatar

craft the code in Perl6

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implement the same function as in “craft the code in clojure” “http://tapestryjava.blogspot.com/2013/02/crafting-code-in-clojure.html

use v6;
sub sorted_keys(%map1,%map2) {
my @keys = %map1.keys, %map2.keys;
if @keys { join(",", @keys.uniq.sort) }
else {"<none>"}
}
my %map1 = 1..6;
my %map2 = 3..10;
say sorted_keys(%map1,%map2);
# vim: filetype=perl6:\n
view raw merge_map_keys.pl hosted with ❤ by GitHub
Unknown's avatar

swap in C

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long time no see, C!

I come to see again, finally.

# include <stdio.h>
void swap0(int a, int b) // change
{
int temp;
printf(" %d\n", temp);
temp = a;
printf(" %d\n", temp);
a = b;
printf(" %d\n", a);
b = temp;
printf(" %d\n", temp);
}
void swap1(int* a, int* b) //do not change
{
int* temp;
printf(" %d\n", *temp);
temp = a;
printf(" %d\n", *temp);
a = b;
printf(" %d\n", *a);
b = temp;
printf(" %d\n", *temp);
}
void swap2(int* a, int* b) // change
{
int temp;
printf(" %d\n", temp);
temp = *a;
printf(" %d\n", temp);
*a = *b; // same with a=b
printf(" %d\n", *a);
*b = temp;
printf(" %d\n", temp);
}
int main()
{
int x = 10;
int y = 20;
printf("%d, %d\n", x, y);
swap1(&x,&y);
printf("%d, %d\n", x, y);
return 0;
}
view raw swap.c hosted with ❤ by GitHub
Unknown's avatar

5 decimal places of pi

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“Given that Pi can be estimated using the function 4 * (1 – 1/3 + 1/5 – 1/7 + …) with more terms giving greater accuracy, write a function that calculates Pi to an accuracy of 5 decimal places.” http://programmers.blogoverflow.com/2012/08/20-controversial-programming-opinions/

import scala.math._
/* cacluate pi
Pi = 4*(1 - 1/3 + 1/5 -1/7+....)
write a function that calculates pi to an accuracy of 5 decimal places
*/
// 1/(2*x+1)*4<1e-6
//4*1e6<2*x+1
// x>(4*1e6-1)/2
// x>2*1e6
def npi(n: Int) = pow(-1,n)/(2*n+1)
val N: Int = 2e6.toInt ;
val pi = (0 to N).map(npi).sum*4
println(pi)
// calculate the area of a circle
def circleArea(r:Double) = pi*r*r
val a = 3
println(circleArea(3))
// vim: set ts=4 sw=4 et:
view raw pi_area.scala hosted with ❤ by GitHub
Unknown's avatar

Cellular Automaton

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Elementary Cellular Automaton

sub deci_bin($n) {
return $n if $n==0 || $n==1;
my $k = $n div 2;
my $b = $n % 2;
my $E = deci_bin($k);
return $E~$b;
}
sub automata($rule,$row) {
my @keys="111","110","101","100","011","010","001","000";
my @vals=substr(deci_bin($rule).comb.reverse.join ~'0'x 8,0,8).comb.reverse;
my %rule= @keys Z, @vals;
my @automata="0"x $row ~"1"~"0" x $row;
#say @automata[*-1];
for 1..$row {
my $next='0';
my $i=0;
repeat while $i<=(@automata[*-1].chars)-3 {
my $str=substr(@automata[*-1],$i,3);
$next= $next ~ %rule{$str};
$i++;
}
$next~='0';
push @automata, $next;
}
@automata;
}
sub MAIN($rule,$row) {
for automata($rule, $row) { say $_.subst(rx/'0'/,' ',:g)}; # ; is not allowed after for
}
view raw cell_automata.pl hosted with ❤ by GitHub
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Min Stack II

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# last time, I build a min stack using perl6’s class.
# the problem is that the perl6 already have pop, push, min method.
# so, to solve the problem of name conflict, I have to rename the name.
# but there is another solution.
# use the multi instead of method.
# TIMTOWTDI

class Minstack {
has @.stack;
has @.min;
}
multi push(Minstack $mstack, $item) {
push $mstack.stack, $item;
if $mstack.min==0 or $mstack.min[*-1] > $item {
push $mstack.min, $item;
}
}
multi pop(Minstack $mstack) {
my $item=pop $mstack.stack;
if $item == $mstack.min[*-1] {
pop $mstack.min;
}
return $item;
}
multi min(Minstack $mstack) {
$mstack.min[*-1];
}
my $min=Minstack.new;
push $min, 5;
push $min, 3;
push $min, 10;
push $min, 2;
say(pop $min); # 2
say(min $min); # 3
say(pop $min); # 10
say(min $min); # 3
say(pop $min); # 3
say(min $min); # 5
say(pop $min); # 5
view raw minstack_multi.pl hosted with ❤ by GitHub
Unknown's avatar

Min Stack

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The problem: Min Stack
Design a data structure that provides push and pop operations, like a stack, plus a third operation that finds the minimum element. All three operations must perform in constant time. You may assume that all elements are distinct.

Use perl6’s class to implement

class Minstack {
has @.stack;
has @.min;
method mpush($item) {
push @.stack, $item;
if @.min==0 or @.min[*-1] > $item {
push @.min, $item;
}
}
method mpop() {
my $item=pop @.stack;
if $item == @.min[*-1] {
pop @.min;
}
return $item;
}
method mmin() {
@.min[*-1];
}
}
my $min=Minstack.new;
$min.mpush(5);
$min.mpush(3);
$min.mpush(10);
say $min.mpop();
say $min.mmin();
view raw Min_stack.pl hosted with ❤ by GitHub

TODO: use multi……

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TODO list in perl6

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1 -TODO list in perl6

1.1 basic function

sub view ($file='todo.org') {
my $todo=open "/home/echo/Dropbox/todo/$file";
my @lines= $todo.lines;
$todo.close;
say " there are "~ +@lines ~ " tasks";
my $order=1;
for @lines -> $line {
say "$order"~"."~"$line";
$order++;
}
}
sub viewdone() {
view("done.org");
}
sub add() {
my $task= prompt "add a task,please\n xxxxxxxxxxxxxxxx\n";
my $todo=open '/home/echo/Dropbox/todo/todo.org',:a ;
$todo.say($task);
$todo.close;
say "adding...task\n\n "~ "$task\n";
}
sub done() {
my $todo=open '/home/echo/Dropbox/todo/todo.org';
my %tasks;
my $i=1;
for $todo.lines -> $line {
say "$i"~"."~"$line";
%tasks{$i}=$line;
$i++;
}
$todo.close;
my $task = prompt "done task number?\n";
my $done = open '/home/echo/Dropbox/todo/done.org',:a;
$done.say(%tasks{$task});
%tasks.delete($task);
my $write = open '/home/echo/Dropbox/todo/todo.org',:w;
for %tasks.values {
$write.say($_);
}
$write.close;
}
view raw todo.pl hosted with ❤ by GitHub

1.2 interact with the outside;

1.2.1 dispatch-using hash

sub MAIN ($op="v"){ #$op="v" eqv $op='v'
my %All = v=>&view, a=>&add, d =>&done, vd=&viewdone;
%All{$op}();
}
view raw tod_dispatch_table.pl hosted with ❤ by GitHub

1.2.2 dispathc-using multi

multi MAIN('a'){ view ; add ;}
multi MAIN('v'){ view ;}
multi MAIN('d'){ done ;}
multi MAIN('vd'){ viewdone;}
view raw todo_multi.pl hosted with ❤ by GitHub