Perl Weekly Challenge 016 and 017

I decided to take a shot at some tasks from the Perl Weekly Challenge.

Challenge 016, Task #1

The Pythagoras Pie Puzzle

At a party a pie is to be shared by 100 guest. The first guest gets 1% of the pie, the second guest gets 2% of the remaining pie, the third gets 3% of the remaining pie, the fourth gets 4% and so on.

My Code

sub eat {
    state $cake = 100;
    given $cake * $^share/100 {
        $cake -= $_;
        $_;
    }
}

.put for (1..100).map(&eat).pairs.sort(-*.value)[^5];

Script Output

9       6.281565095552947
10      6.21874944459741773
8       6.21253690768973
11      6.037840369845492849
7       6.002451118541

The 10th guest gets the largest share of the pie at 6.28%.

Challenge 017, Task #1

The Ackermann Function

Create a script to demonstrate Ackermann function. The Ackermann function is defined as below, m and n are positive number:

A(m, n) = n + 1                  if m = 0
A(m, n) = A(m - 1, 1)            if m > 0 and n = 0
A(m, n) = A(m - 1, A(m, n - 1))  if m > 0 and n > 0

My Code

proto A($m, $n) { %.{"$m,$n"} //= {*} }
multi A(0, $n) { $n + 1 }
multi A($m, 0) { A($m - 1, 1) }
multi A($m, $n) { A($m - 1, A($m, $n - 1)) }

sub MAIN(UInt $m, UInt $n) { say A($m, $n) }

An anonymous hash is used to cache already computed values within the proto.