Merge pull request #4135 from andemark/branch-for-challenge-114

Branch for challenge 114

1 files changed, 46 insertions, 0 deletions

diff --git a/challenge-114/mark-anderson/raku/ch-1.raku b/challenge-114/mark-anderson/raku/ch-1.raku
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+#!/usr/bin/env raku
+
+use Test;
+plan 9;
+
+is next-palindrome-number(3),                                             4;
+is next-palindrome-number(9),                                            11;
+is next-palindrome-number(999),                                        1001;
+is next-palindrome-number(1234),                                       1331;
+is next-palindrome-number(1999),                                       2002;
+is next-palindrome-number(4321),                                       4334;
+is next-palindrome-number(4444),                                       4554;
+is next-palindrome-number(500006),                                   501105;
+is next-palindrome-number(90000056780000000000000), 90000056780008765000009; 
+
+multi next-palindrome-number($N where * == 9) { 11 } 
+
+multi next-palindrome-number($N)
+{
+    my ($left, $middle) = partition($N);
+    my $next = $left ~ $middle ~ $left.flip;
+
+    while $next <= $N
+    {
+        $next = ($left ~ $middle) + 1;
+        $next ~= $next.substr(^$left.chars).flip;
+    }
+
+    $next;
+}
+
+sub partition($N)
+{    
+    my @N = $N.comb;
+    my $mid = @N.elems div 2;
+    my @left = @N[^$mid];
+    my $middle = q{};
+    my @right = @N[$mid..*];
+
+    unless @left.end == @right.end
+    {
+        $middle = @right.shift;
+    }
+
+    @left.join, $middle;
+}