Merge pull request #2729 from dcw803/master

committed my solutions to this week's questions

3 files changed, 150 insertions, 65 deletions

diff --git a/challenge-085/duncan-c-white/README b/challenge-085/duncan-c-white/README
index 45d0cc6f4e..53a59c4fc8 100644
--- a/challenge-085/duncan-c-white/README
+++ b/challenge-085/duncan-c-white/README
@@ -1,91 +1,50 @@
-Task 1: "Reverse Integer
+Task 1: "Triplet Sum
 
-You are given an integer $N.
+You are given an array of real numbers greater than zero.
 
-Write a script to reverse the given integer and print the result. Print
-0 if the result doesn't fit in 32-bit signed integer.
-
-The number 2,147,483,647 is the maximum positive value for a 32-bit
-signed binary integer in computing.
+Write a script to find if there exists a triplet (a,b,c) such that 1 <
+a+b+c < 2. Print 1 if you succeed otherwise 0.
 
 Example 1:
 
-	Input: 1234
-	Output: 4321
+	Input: @R = (1.2, 0.4, 0.1, 2.5)
+	Output: 1 as 1 < 1.2 + 0.4 + 0.1 < 2
 
 Example 2:
 
-	Input: -1234
-	Output: -4321
+	Input: @R = (0.2, 1.5, 0.9, 1.1)
+	Output: 0
 
 Example 3:
 
-	Input: 1231230512
-	Output: 0
-
+	Input: @R = (0.5, 1.1, 0.3, 0.7)
+	Output: 1 as 1 < 0.5 + 1.1 + 0.3 < 2
 
-My notes: simple, clearly defined: only tricky bit is the overflow detection
-as Perl **doesn't** use 32bit integers.
+My notes: simple, I think it means "pick any 3 elements a, b and c from the
+array and determine if any a,b,c triple sums to between 1 and 2", although both
+successful examples show 3 ADJACENT elements a, b and c...
 
 
-Task 2: "Find Square
+Task 2: "Power of Two Integers
 
-You are given a binary matrix of size m x n (all elements are 1 or 0).
+You are given a positive integer $N.
 
-Write a script to find the count of squares having all four corners set as 1.
+Write a script to find if it can be expressed as a ** b where a > 0 and
+b > 1. Print 1 if you succeed otherwise 0.
 
 Example 1:
 
-Input: [ 0 1 0 1 ]
-       [ 0 0 1 0 ]
-       [ 1 1 0 1 ]
-       [ 1 0 0 1 ]
-
-Output: 1
-
-Explanation:
-	There is one square (3x3) in the given matrix with four corners
-	as 1 starts at r=1;c=2.
-
-	[ 1 0 1 ]
-	[ 0 1 0 ]
-	[ 1 0 1 ]
+Input: 8
+Output: 1 as 8 = 2 ** 3
 
 Example 2:
 
-Input: [ 1 1 0 1 ]
-       [ 1 1 0 0 ]
-       [ 0 1 1 1 ]
-       [ 1 0 1 1 ]
-
-Output: 4
-
-Explanation:
-	There is one square (4x4) in the given matrix with four corners
-	as 1 starts at r=1;c=1.
-	There is one square (3x3) in the given matrix with four corners as 1
-	starts at r=1;c=2.
-	There are two squares (2x2) in the given matrix with four corners as
-	1. First starts at r=1;c=1 and second starts at r=3;c=3.
-
-Example 3:
-
-Input: [ 0 1 0 1 ]
-       [ 1 0 1 0 ]
-       [ 0 1 0 0 ]
-       [ 1 0 0 1 ]
-
+Input: 15
 Output: 0
 
-My notes: clearly defined, seems straightforward.
-
-Have to define the Input format: CSV rows on command line so example 3 is:
-./ch-2.pl 0,1,0,1 1,0,1,0 0,1,0,0 1,0,0,1
+Example 3:
 
-Initially, I found all RECTANGLES inside the matrix, then rejected those that
-weren't SQUARES - before ever checking whether the corner elements were all 1.
-Find that in ch-2-firstattempt.pl
+Input: 125
+Output: 1 as 125 = 5 ** 3
 
-But then I improved that, by directly finding all SQUARES inside the
-matrix, then checked whether their corner elements were all 1.
-This reduces 4 nested loops to 3..
+My notes: clearly defined, not quite sure how to do it so.. let's brute force
diff --git a/challenge-085/duncan-c-white/perl/ch-1.pl b/challenge-085/duncan-c-white/perl/ch-1.pl
new file mode 100755
index 0000000000..8407c6b6a4
--- /dev/null
+++ b/challenge-085/duncan-c-white/perl/ch-1.pl
@@ -0,0 +1,65 @@
+#!/usr/bin/perl
+#
+# Task 1: "Triplet Sum
+#
+# You are given an array of real numbers greater than zero.
+# 
+# Write a script to find if there exists a triplet (a,b,c) such that 1 <
+# a+b+c < 2. Print 1 if you succeed otherwise 0.
+# 
+# Example 1:
+# 
+# 	Input: @R = (1.2, 0.4, 0.1, 2.5)
+# 	Output: 1 as 1 < 1.2 + 0.4 + 0.1 < 2
+# 
+# Example 2:
+# 
+# 	Input: @R = (0.2, 1.5, 0.9, 1.1)
+# 	Output: 0
+# 
+# Example 3:
+# 
+# 	Input: @R = (0.5, 1.1, 0.3, 0.7)
+# 	Output: 1 as 1 < 0.5 + 1.1 + 0.3 < 2
+# 
+# My notes: simple, I think it means "pick any 3 elements a, b and c from the
+# array and determine if any a,b,c triple sums to between 1 and 2", although
+# both successful examples show 3 ADJACENT elements a, b and c...
+#
+
+use strict;
+use warnings;
+use feature 'say';
+use Function::Parameters;
+use Data::Dumper;
+
+die "Usage: triplet-sum array\n" unless @ARGV;
+my @x = @ARGV;
+
+#
+# my $istriplet = findtriplet( @x );
+#	Find whether the sum of any triplet of elements from @x
+#	has a sum between 1 and 2.  Return 1 iff one does; return 0 otherwise.
+#
+fun findtriplet( @x )
+{
+	my $n = @x;
+	foreach my $apos (0..$n-3)
+	{
+		my $a = $x[$apos];
+		foreach my $bpos ($apos+1..$n-2)
+		{
+			my $b = $x[$bpos];
+			foreach my $cpos ($bpos+1..$n-1)
+			{
+				my $c = $x[$cpos];
+				my $sum = $a+$b+$c;
+				return 1 if $sum > 1 && $sum < 2;
+			}
+		}
+	}
+	return 0;
+}
+
+my $istriplet = findtriplet( @x );
+say $istriplet;
diff --git a/challenge-085/duncan-c-white/perl/ch-2.pl b/challenge-085/duncan-c-white/perl/ch-2.pl
new file mode 100755
index 0000000000..5794389ed5
--- /dev/null
+++ b/challenge-085/duncan-c-white/perl/ch-2.pl
@@ -0,0 +1,61 @@
+#!/usr/bin/perl
+#
+# Task 2: "Power of Two Integers
+# 
+# You are given a positive integer $N.
+# 
+# Write a script to find if it can be expressed as a ** b where a > 0 and
+# b > 1. Print 1 if you succeed otherwise 0.
+# 
+# Example 1:
+# 
+# Input: 8
+# Output: 1 as 8 = 2 ** 3
+# 
+# Example 2:
+# 
+# Input: 15
+# Output: 0
+# 
+# Example 3:
+# 
+# Input: 125
+# Output: 1 as 125 = 5 ** 3
+# 
+# My notes: clearly defined, not quite sure how to do it so.. let's brute force
+# 
+
+use strict;
+use warnings;
+use feature 'say';
+use Function::Parameters;
+use Data::Dumper;
+
+die "Usage: power N\n" unless @ARGV==1;
+my $n = shift;
+
+#
+# my $isatob = atob( $n );
+#	Return 1 iff $n if a**b where a>0 && b>1
+#
+fun atob( $n )
+{
+	return 1 if $n==1;
+	my $limit = int(sqrt($n));
+	foreach my $a (2..$limit)
+	{
+		next unless $n % $a == 0;
+		my $x = $n/$a;
+		while( $x>1 && $x % $a == 0 )
+		{
+			$x /= $a;
+		}
+		return 1 if $x==1;
+	}
+	return 0;
+}
+
+
+my $result = atob( $n );
+say $result;
+