Solution to task 1 challenge-105

1 files changed, 46 insertions, 0 deletions

diff --git a/challenge-105/wanderdoc/perl/ch-1.pl b/challenge-105/wanderdoc/perl/ch-1.pl
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+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+You are given positive numbers $N and $k. Write a script to find out the $Nth root of $k.
+Example
+Input: $N = 5, $k = 248832 Output: 12
+Input: $N = 5, $k = 34 Output: 2.02
+=cut
+
+
+
+
+
+
+
+use Test::More;
+use List::Util qw(reduce);
+
+sub nthroot # newton algorithm
+{
+     my ( $n, $k, $precision ) = @_;
+
+     $precision //= 5;
+
+     my $x0 = $k / $n;
+     my $x1; 
+          
+     while (1)
+     {
+          $x1 = (1 / $n) * 
+               ( ( $n - 1 ) * $x0 + $k / ( reduce { $a * $b } ($x0) x ($n - 1) ) );
+          last if sprintf("%.${precision}f", $x0) == sprintf("%.${precision}f", $x1);
+          $x0 = $x1;
+     }
+     return sprintf("%.${precision}f", $x1) + 0;
+}
+
+
+is(nthroot(5, 248832), 12,  'Example 1');
+is(nthroot(5, 34, 2), 2.02, 'Example 2');
+is(nthroot(2, 2, 8), 1.41421356, 'Example 3'); 
+is(nthroot(5, 222), 2.94626, 'Example 4');
+is(nthroot(123, 987), 1.05766, 'Example 5');
+done_testing();
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