TASK #1 › Count Number
Task
You are given a positive number $N.
Write a script to count number and display as you read it.
My solution
The task mentions a positive number (as opposed to a positive integer), but didn't give an example of what to do with a dot, so my script will only accept integers.
This is one of those tasks where I'm interested in how other Team PWC members attempt it. I'm sure there is a way to do this purely with a regular expression, but after about 10 minutes of trying to find the correct syntax, I abandoned that idea.
In the end I went with something that just works™. I take the first character, and then use a regular expression pattern /^($char+)(.*)$/ to remove the one or more occurrences of that character. I continue until the string is empty.
Then it is simply a matter of displaying the new number made up of the length and the number for each match.
Examples
» ./ch-1.pl 1122234
21321314
» ./ch-1.pl 2333445
12332415
» ./ch-1.pl 12345
1112131415
TASK #2 › Jump Game
Task
You are given an array of positive numbers @N, where value at each index determines how far you are allowed to jump further.
Write a script to decide if you can jump to the last index. Print 1 if you are able to reach the last index otherwise 0.
My solution
Like with the first task it is suggested that any positive number is valid. However zero - which is not a positive number - is used in an example. It also doesn't make sense to have a fractional number, as you can't jump in non whole numbers. So for this task, I only allow non-negative integers.
For this tasks, I have a value $position which records my current position.
- I return 1 if the current position is the last index (array length - 1). In this case we have landed on the last index.
- If the current position is greater than the last index I return 0. We have overshot the last index, and therefore no solution is possible.
- I also return 0 if the value at the current position is
0. In this case we will have an endless loop that will never move forward. - I then increase the
$positionvariable by the value of the current index, and repeat the above tests.
Examples
» ./ch-2.pl 1 2 1 2
1
» ./ch-2.pl 2 1 1 0 2
0
Top comments (1)
And without failure, the first Perl pull request (by Neil) has the solution to the first task using just a regular expression. As always, I never look at other people's solutions until after I have submitted my own.
My failure was I was trying to use
\1for the inner match when I actually wanted\2#TIL