# Commits

committed 3845703

Add the solution to Euler #113.

• Participants
• Parent commits 5c0fa61

# File project-euler/113/euler-113.pl

+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+
+Working from left-to-right if no digit is exceeded by the digit to its left it is called an increasing number; for example, 134468.
+
+Similarly if no digit is exceeded by the digit to its right it is called a decreasing number; for example, 66420.
+
+We shall call a positive integer that is neither increasing nor decreasing a "bouncy" number; for example, 155349.
+
+Clearly there cannot be any bouncy numbers below one-hundred, but just over half of the numbers below one-thousand (525) are bouncy. In fact, the least number for which the proportion of bouncy numbers first reaches 50% is 538.
+
+Surprisingly, bouncy numbers become more and more common and by the time we reach 21780 the proportion of bouncy numbers is equal to 90%.
+
+Find the least number for which the proportion of bouncy numbers is exactly 99%.
+
+=cut
+
+my @counts = (0,0);
+for (my \$n = 1; ; \$n++)
+{
+    my \$s = join "",sort { \$a <=> \$b } split//,\$n;
+
+    \$counts[(\$n eq \$s) || (\$n eq scalar(reverse(\$s))) || 0]++;
+
+=begin foo
+    if (\$n == 538)
+    {
+        print "@counts\n";
+    }
+=end foo
+
+=cut
+
+    if (\$n % 100_000 == 0)
+    {
+        print "\$n: @counts\n"
+    }
+
+    if (\$counts[1] * 100 == \$n)
+    {
+        print "Least n = \$n\n";
+        exit(0);
+    }
+}