improvement

2 files changed, 63 insertions, 57 deletions

diff --git a/challenge-076/cheok-yin-fung/perl/ch-1.pl b/challenge-076/cheok-yin-fung/perl/ch-1.pl
index 51275f8742..c790d2c0e5 100644
--- a/challenge-076/cheok-yin-fung/perl/ch-1.pl
+++ b/challenge-076/cheok-yin-fung/perl/ch-1.pl
@@ -6,7 +6,7 @@
 # Usage: ch-1.pl $N
 
 # Given the Goldbach's conjecture conjecture is verified 
-# for n < 4 000 000 000 000 000 000 000 000 
+# for n < 4 000 000 000 000 000 000 
 # ( source: mathworld.wolfram.com )
 
 use strict;
@@ -37,7 +37,7 @@ if ($V == 2) {
 }
 
 if ($V == 4) {
-    print "2\nas 2 + 2 = 4.\n";
+    print "2\nas 2 + 2 = 4 and 4 is not a prime.\n";
     exit;
 }
 
@@ -53,6 +53,7 @@ if ($V % 2 == 0) {
     for (keys %oddprime) {
         if ($oddprime{$V-$_}) {
             print "as $_", " + ", $V-$_," = $V.\n" ;
+            last;
         }
     }
 } 
@@ -61,14 +62,18 @@ else {
     if ($oddprime{$V}) {
         print "1\nas $V is a prime.\n";
     } 
-    elsif ($oddprime{$V-2} == 1) {
-            print "2\nas 2 + " ,$V-2, " = $V.\n" ,
+    elsif ($oddprime{$V-2}) {
+            print "2\nas 2 + " ,$V-2, " = $V\nand $V is not a prime.\n" ,
         }
         else {
             print "3\n";
             for (keys %oddprime) {
                 if ($oddprime{$V-3-$_}) {
-                    print "as 3 + $_", " + ", $V-$_-3," = $V.\n";
+                    print "3 + $_", " + ", $V-$_-3," = $V .\n";
+                    print "The answer can't be 1 or 2 because",
+                          " neither ", $V-2 ," nor $V is a prime; and\n", 
+                          " there are no even primes except 2\n",
+                          " (two odd primes sum to an even number).\n";
                     last;
                 }
             }
diff --git a/challenge-076/cheok-yin-fung/perl/ch-2.pl b/challenge-076/cheok-yin-fung/perl/ch-2.pl
index 28c1dc62d9..1642231842 100644
--- a/challenge-076/cheok-yin-fung/perl/ch-2.pl
+++ b/challenge-076/cheok-yin-fung/perl/ch-2.pl
@@ -1,8 +1,10 @@
-# Perl Weekly Challenge #076 Task 2
-# Word Search
-# task statement:
-# Write a script that takes two file names. The first file would contain word search grid as shown below. The second file contains list of words, one word per line. You could even use local dictionary file.
-#
+# Perl Weekly Challenge #076 Task 2 Word Search
+# task statements:
+# Write a script that takes two file names. 
+# The first file would contain word search grid 
+# as shown [below]. The second file contains list of words, 
+# one word per line. You could even use 
+# local dictionary file.
 # Usage: ch-2.pl gridfile dictfile 
 
 use strict;
@@ -58,12 +60,7 @@ my $ylen = scalar @matrix;
 # ==============
 
 sub joinline {
-    my @temp = @_;
-    @temp = grep {defined($_)} @temp;
-    # without the `grep {defined($_)}`, the program crashes
-    #  while the input grid is a vertically longer rectangle.
-    # I haven't figured out why. Aug 3rd 2020
-    return lc(join "", @temp);
+    return lc(join "", @_);
 }
 
 sub reversestring {
@@ -93,43 +90,45 @@ for my $j (0..$xlen-1) {
 # ==============================
 sub find_diagonal {
     my @mat = @{$_[0]};
-    my @ulefttolright;
-    my @extra_dia;
-    my $xlen_t = scalar @{$mat[0]};
-    my $ylen_t = scalar @mat;
-    $ulefttolright[0] = joinline map {${$mat[$_]}[$_]} (0..$ylen_t-1);
-    $ulefttolright[1] = reversestring $ulefttolright[0];
-
-    if ($xlen_t >= $ylen_t) {         
-        for my $c (0..$xlen_t-$ylen_t) {
-            $ulefttolright[$c*2] = joinline 
-                    map {${$mat[$_]}[$c+$_]} (0..$ylen_t-1) ; 
-            $ulefttolright[$c*2+1] = reversestring $ulefttolright[$c*2]; 
+    my @ulefttolright = ();
+    my @extra_dia = ();
+    my $t_xlen = scalar @{$mat[0]};
+    my $t_ylen = scalar @mat;
+    my $t_limit = ($t_xlen > $t_ylen) ? $t_ylen : $t_xlen;
+    my $t_diff = ($t_xlen > $t_ylen) ? $t_xlen - $t_ylen : $t_ylen - $t_xlen;
+
+    if ($t_xlen >= $t_ylen) {         
+        for my $c (0..$t_diff) {                          
+            $ulefttolright[$c*2] = joinline                            
+                    map {${$mat[$_]}[$c+$_]} (0..$t_ylen-1) ;        
+            $ulefttolright[$c*2+1] = reversestring $ulefttolright[$c*2];   
         }
 
-         for my $c (0..$ylen_t-2) {
-            $extra_dia[$c*4] = joinline 
-                map {${$mat[$_]}[$xlen_t-$ylen_t+$c+$_]} (0..$ylen_t-$c-1) ; 
-            $extra_dia[$c*4+1] = reversestring $extra_dia[$c*4];
-            $extra_dia[$c*4+2] = joinline 
-                    map {${$mat[$c+$_]}[$_]} (0..$ylen_t-$c-1) ; 
-            $extra_dia[$c*4+3] = reversestring $extra_dia[$c*4+2];
+        for my $d (0..$t_limit-2) {                     
+            $extra_dia[$d*4] = joinline 
+                map {${$mat[$_]}[$t_diff+$d+1+$_]} (0..$t_limit-$d-2) ; 
+            $extra_dia[$d*4+1] = reversestring $extra_dia[$d*4];
+            $extra_dia[$d*4+2] = joinline 
+                map {${$mat[$d+1+$_]}[$_]} (0..$t_limit-$d-2) ;
+            $extra_dia[$d*4+3] = reversestring $extra_dia[$d*4+2];
         }
     }
     else {
-        for my $c (0..$ylen_t-$xlen_t) {
+        for my $c (0..$t_diff) {
             $ulefttolright[$c*2] = joinline  
-                    map {${$mat[$_+$c]}[$_]} (0..$xlen_t-1) ; 
+                map {${$mat[$_+$c]}[$_]} (0..$t_xlen-1) ; 
             $ulefttolright[$c*2+1] = reversestring $ulefttolright[$c*2]; 
         }
-         for my $c (0..$xlen_t-2) {
-              $extra_dia[$c*4] = joinline 
-                  map {${$mat[$ylen_t-$xlen_t+$c+$_]}[$_]} (0..$xlen_t-$c-1) ;
-             $extra_dia[$c*4+1] = reversestring $extra_dia[$c*4];
-             $extra_dia[$c*4+2] = joinline
-                map {${$mat[$_]}[$c+$_]} (0..$xlen_t-$c-1) ; 
-             $extra_dia[$c*4+3] = reversestring $extra_dia[$c*4+2];
+         for my $d (0..$t_limit-2)  {        
+             $extra_dia[$d*4] = joinline 
+                 map {${$mat[$t_diff+$d+1+$_]}[$_]} (0..$t_limit-$d-2) ;
+             $extra_dia[$d*4+1] = reversestring $extra_dia[$d*4];
+             $extra_dia[$d*4+2] = joinline
+                 map {${$mat[$_]}[$d+1+$_]} (0..$t_limit-$d-2) ; 
+             $extra_dia[$d*4+3] = reversestring $extra_dia[$d*4+2];
         }
+
+
     }
     return (@ulefttolright, @extra_dia);
 }
@@ -142,12 +141,12 @@ sub find_diagonal {
 sub vertical_reflection {
     my @mat = @{$_[0]};
     my @newmat;
-    my $xlen_t = scalar @{$mat[0]};
-    my $ylen_t = scalar @mat;
-    for my $i (0..$xlen_t-1) {
+    my $t_xlen = scalar @{$mat[0]};
+    my $t_ylen = scalar @mat;
+    for my $i (0..$t_ylen-1) {
         @{$newmat[$i]} = ();
-        for my $j (0..$ylen_t-1) {
-            ${$newmat[$i]}[$j] = ${$mat[$i]}[$ylen_t-1-$j];
+        for my $j (0..$t_xlen-1) {
+            ${$newmat[$i]}[$j] = ${$mat[$i]}[-1-$j];
         }
     }
     return @newmat;
@@ -160,29 +159,31 @@ my @antidiagonal = find_diagonal( \@newmatrix);
 # ===========================
 
 
-
 # main dish:
 
 my %unique;
 
 for my $word (@dictwords) {
-    for (@rowline,@colline,@diagonal,@antidiagonal) { 
-        if (not($unique{$word}) && defined($_) && $_ =~ /$word/ ) {
+    for (@rowline,@colline,@diagonal,@antidiagonal) {
+       if (defined $_) { 
+        if ($_ =~ /$word/ && not($unique{$word}) ) {
             print $word, " ";
             $unique{$word} = 1;
         } 
+       }
     }
 }
-print "\n";
 
+print "\n";
 
 # grid: as given in task statement
-# words list: 
+# word list: 
 # https://www.oxfordlearnersdictionaries.com/wordlists/oxford3000-5000
 # words with length more than or equal to 5 in the grid:
 #   align broad constitution depart enter midst social virus
 #
 # Running time
-# real	0m0.314s
-# user	0m0.302s
-# sys	0m0.012s
+# real	0m0.254s
+# user	0m0.249s
+# sys	0m0.004s
+