Merge pull request #6406 from steve-g-lynn/branch-for-challenge-172

improved

3 files changed, 37 insertions, 22 deletions

diff --git a/challenge-172/steve-g-lynn/julia/ch-1.jl b/challenge-172/steve-g-lynn/julia/ch-1.jl
index 0c4aba99b8..fa3f9bda66 100755
--- a/challenge-172/steve-g-lynn/julia/ch-1.jl
+++ b/challenge-172/steve-g-lynn/julia/ch-1.jl
@@ -3,16 +3,21 @@
 using Primes
 
 function prime_partition(m::Int, n::Int)::Matrix{Int}
-	retval=Array{Int}(undef,0,n)                
+
+	if (n > m/2)
+		return Array{Int}(undef,0,n)
+	end                
+
+	retval=Array{Int}(undef,0,n)
 	if (n==2)
 		for i in primes(m ÷ 2)
 			if (isprime(m-i))
 				retval=[retval;i m-i]
 			end
+			if ( (m % 2) > 0) #for odd m: (m-i) is even for i > 2
+				break
+			end
 		end
-		retval=sort_partition(retval)
-		retval=delete_equal_rows(retval)
-		return retval
 	end
 	if  (n > 2)
 		for i in primes(m ÷ n)
@@ -22,10 +27,10 @@ function prime_partition(m::Int, n::Int)::Matrix{Int}
 				retval=[retval; (i .* ones(Int,sizep[1])) p]
 			end
 		end
-		retval=sort_partition(retval)
-		retval=delete_equal_rows(retval)
-		return retval
 	end
+	retval=sort_partition(retval)
+	retval=delete_equal_rows(retval)
+	return retval
 end
 
 function sort_partition(p::Matrix{Int})::Matrix{Int}
@@ -47,4 +52,3 @@ println(prime_partition(18,2))
 println(prime_partition(19,3))
 println(prime_partition(20,4))
 
-
diff --git a/challenge-172/steve-g-lynn/perl/ch-1.pl b/challenge-172/steve-g-lynn/perl/ch-1.pl
index 3d81c9f72c..5d8bb723f6 100755
--- a/challenge-172/steve-g-lynn/perl/ch-1.pl
+++ b/challenge-172/steve-g-lynn/perl/ch-1.pl
@@ -15,21 +15,24 @@ print &prime_partition(20,4),"\n";
 
 sub prime_partition {
 	my ($m, $n)=@_;
-	
+
 	if ($m > $MAXPRIMES) {
 		$primes = $primes -> append(primes($MAXPRIMES, $m));
 		$MAXPRIMES = $m;
 	}
 
+	if ($n > $m/2) { return zeros($n,0); }
+
 	my $retval=zeros($n,0);
-	
+
 	#-- $n == 2
 	if ($n==2) {
 		for my $prime ($primes -> list) {
 			if (is_prime($m - $prime)) {
-				$retval = $retval->glue(1, 
+				$retval = $retval->glue(1,
 					pdl([$m - $prime, $prime]));
 			}
+			last unless ($m % 2 ==0); #-- for odd m, m-i will be even for all i>2
 			last if ($prime > int($m / 2));
 		}
 	}
@@ -40,7 +43,7 @@ sub prime_partition {
 			my $p1 = &prime_partition($m - $prime, $n - 1);
 			if ( ($p1 -> dim(1)) > 0){
 				$p1=append($prime, $p1);
-				$retval = $retval->glue(1,$p1);			
+				$retval = $retval->glue(1,$p1);
 			}
 			last if ($prime > int($m / $n));
 		}
diff --git a/challenge-172/steve-g-lynn/raku/ch-1.p6 b/challenge-172/steve-g-lynn/raku/ch-1.p6
index 8e1ce34034..a81b15eb1d 100755
--- a/challenge-172/steve-g-lynn/raku/ch-1.p6
+++ b/challenge-172/steve-g-lynn/raku/ch-1.p6
@@ -10,21 +10,24 @@ say &prime-partition(18,2);
 say &prime-partition(19,3);
 say &prime-partition(20,4);
 
+say &distinct-prime-partition(19,3);
+
 multi sub prime-partition (Int $m where $m > 0, Int $n where $n==2) {
 	($n > ($m div 2)) && (return ());
-	
+
 	my @pp=();
-	
+
 	if ($m > $MAXPRIMES) {
 		push @primes, $p.primes($MAXPRIMES,$m);
-		$MAXPRIMES = $m;		
-	}	
+		$MAXPRIMES = $m;
+	}
 
 	for (@primes) -> $prime {
 		if ( ($m - $prime).is-prime ) {
 			push @pp, BagHash.new($prime,$m-$prime);
 		}
-		last if ($prime > ($m div 2));  
+		last unless ($m %% 2); #for odd m, m-i always even for prime i > 2
+		last if ($prime > ($m div 2));
 	}
 	return @pp.unique(as => BagHash, with => &[eqv] );
 }
@@ -33,13 +36,13 @@ multi sub prime-partition (Int $m where $m > 0, Int $n where $n==2) {
 multi sub prime-partition (Int $m where $m > 0, Int $n where $n > 2) {
 
 	($n > ($m div 2)) && (return ());
-	
+
 	my @pp=();
-	
+
 	if ($m > $MAXPRIMES) {
 		push @primes, $p.primes($MAXPRIMES,$m);
-		$MAXPRIMES = $m;		
-	}	
+		$MAXPRIMES = $m;
+	}
 
 	for (@primes) -> $prime {
 		my @p1 = &prime-partition($m - $prime, $n - 1);
@@ -50,7 +53,12 @@ multi sub prime-partition (Int $m where $m > 0, Int $n where $n > 2) {
 			}
 		}
 		@pp.append(@p1);
-		last if ($prime > ($m div 3));	
+		last if ($prime > ($m div 3));
 	}
 	return @pp.unique(as => BagHash, with => &[eqv] );
 }
+
+#--distinct prime partitions, as specified in challenge
+sub distinct-prime-partition (Int $m where $m > 0, Int $n where $n > 2) {
+	return ($p.primes($m-2)).combinations($n).grep(*.sum==$m);
+}