Mohammad Sajid Anwar manwar

✌️

Undercover Contributor

2022 White Camel Awardee. CPAN Contributor. Co-editor of Perl Weekly newsletter. Run The Weekly Challenge. Indian by birth, British by choice.

Last active October 27, 2017 14:19

Git command helper

	- Rename / Delete Tag

	$ git tag new_tag_name old_tag_name
	$ git tag -d old_tag_name

	- Tag a git commit

	$ git checkout <commit id>
	$ git tag <tag name>
	$ git push origin <tag name>

Last active August 29, 2015 14:06

Tmux command helper

	- Detach tmux session

	Ctrl + B then press D

	- Attach tmux session

	tmux attach

	- Find the tmux version installed

Last active August 29, 2015 14:06

Perl Tricks

	- Magic of '/r' as shown below:

	my @new = map { s/foo/bar/r } @old;

	Compared with the old way:

	my @new = map { (my $tmp = $_) =~ s/foo/bar/; $tmp } @old;

	- To find the full path of the installed module (Modern Perl 2014, page 148)

Created November 3, 2014 11:04

Random Thoughts

	- Simple regex to validate UK postcode

	/[A-Z]{1,2}[0-9][0-9A-Z]?\s?[0-9][A-Z]{2}/gi

Last active August 29, 2015 14:08

Shortest Path Algorithm for Unweighted Graphs

	Source: http://courseweb.sp.cs.cmu.edu/~cs200/lecture22/lecture22.html

	One common use of graphs is to find the shortest path from one place to another. You may have
	at some point used an online program to find driving directions, and you likely had to specify
	if you wanted the shortest route/fastest route. This involves finding the shortest path in a
	weighted graph, but we will make it simpler for now by sticking to an unweighted graph.

	In an unweighted graph, finding the shortest path involves something you already know about -
	breadth-first search. To find the shortest path from a starting vertex s to a vertex v, we see
	if we can get from s to v in one step. If we can, we've found the shortest path from s to v.If

Last active August 29, 2015 14:08

Shortest Path Algorithm for Weighted Graphs

	Source: http://courseweb.sp.cs.cmu.edu/~cs200/lecture22/lecture22.html

	If the graph is weighted, the problem is a bit more complex, but we can still use the ideas we learned
	from the shortest path algorithm for unweighted graphs.

	We keep all of the same information as before. So each vertex is marked as either known or unknown. We
	keep the tentative distance Length for each vertex as in the unweighted case. We again record Path, which
	is the last vertex to cause a change to Length.

	The general algorithm to solve the shortest path problem is known as Dijkstra's Algorithm. Dijkstra's

Last active January 4, 2018 13:07

PostgreSQL Help

	PostgreSQL HELP
	---------------

	1. Conditional constraint

	CREATE UNIQUE INDEX <name> ON <table>(<col 1>,<col 2>,...) WHERE <col 3> IS TRUE;

	2. Check time overlaps

	SELECT <col 1>, <col 2>, ...

Created March 10, 2015 12:16

How to install git on Raspberry Pi

	$ sudo apt-get install gettext

	$ wget https://www.kernel.org/pub/software/scm/git/git-2.3.0.tar.xz

	$ tar -xvf git-2.3.0.tar.xz

	$ cd git-2.3.0/

	$ ./configure --prefix=/usr --with-gitconfig=/etc/gitconfig

Created March 30, 2015 14:16

Generate Magic Square

	#!/usr/bin/perl

	use strict; use warnings;

	my $n = $ARGV[0];
	die "Sorry, must be a positive odd integer.\n"
	unless ((defined $n) && ($n % 2 == 1) && ($n > 0));

	for(my $i=0; $i<$n; $i++) {
	for(my $j=0; $j<$n; $j++) {

Last active August 29, 2015 14:18

Moo tips

	- Adding 'predicate => 1' to an attribute, will create a method has_<attr_name> which
	would return 0 or 1 depending on whether the attribute has any value. In case the
	attribute starts with '_' then it would create _has_<attr_name>. In case we want
	completely different name then we can do so by 'predicate => "my_new_val_check"'.

	- Adding 'clearer => 1' to an attribute, will create a method clear_<attr_name> which
	would clear attribute value including any default assigned. Even if an attribute is
	marked as 'required', it can remove its value, because 'default' and 'required' only
	applies to the constructor.