Task 1: "Reverse Integer

You are given an integer $N.

Write a script to reverse the given integer and print the result. Print
0 if the result doesn't fit in 32-bit signed integer.

The number 2,147,483,647 is the maximum positive value for a 32-bit
signed binary integer in computing.

Example 1:

	Input: 1234
	Output: 4321

Example 2:

	Input: -1234
	Output: -4321

Example 3:

	Input: 1231230512
	Output: 0


My notes: simple, clearly defined: only tricky bit is the overflow detection
as Perl **doesn't** use 32bit integers.


Task 2: "Find Square

You are given a binary matrix of size m x n (all elements are 1 or 0).

Write a script to find the count of squares having all four corners set as 1.

Example 1:

Input: [ 0 1 0 1 ]
       [ 0 0 1 0 ]
       [ 1 1 0 1 ]
       [ 1 0 0 1 ]

Output: 1

Explanation:
	There is one square (3x3) in the given matrix with four corners
	as 1 starts at r=1;c=2.

	[ 1 0 1 ]
	[ 0 1 0 ]
	[ 1 0 1 ]

Example 2:

Input: [ 1 1 0 1 ]
       [ 1 1 0 0 ]
       [ 0 1 1 1 ]
       [ 1 0 1 1 ]

Output: 4

Explanation:
	There is one square (4x4) in the given matrix with four corners
	as 1 starts at r=1;c=1.
	There is one square (3x3) in the given matrix with four corners as 1
	starts at r=1;c=2.
	There are two squares (2x2) in the given matrix with four corners as
	1. First starts at r=1;c=1 and second starts at r=3;c=3.

Example 3:

Input: [ 0 1 0 1 ]
       [ 1 0 1 0 ]
       [ 0 1 0 0 ]
       [ 1 0 0 1 ]

Output: 0

My notes: clearly defined, seems straightforward.

Have to define the Input format: CSV rows on command line so example 3 is:
./ch-2.pl 0,1,0,1 1,0,1,0 0,1,0,0 1,0,0,1

Initially, I found all RECTANGLES inside the matrix, then rejected those that
weren't SQUARES - before ever checking whether the corner elements were all 1.
Find that in ch-2-firstattempt.pl

But then I improved that, by directly finding all SQUARES inside the
matrix, then checked whether their corner elements were all 1.
This reduces 4 nested loops to 3..