Merge pull request #2209 from E7-87-83/master

Cheok-Yin's Submission for PWC 076 

3 files changed, 272 insertions, 0 deletions

diff --git a/challenge-076/cheok-yin-fung/perl/BLOG.txt b/challenge-076/cheok-yin-fung/perl/BLOG.txt
new file mode 100644
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+++ b/challenge-076/cheok-yin-fung/perl/BLOG.txt
@@ -0,0 +1 @@
+http://blogs.perl.org/users/c_y_fung/2020/09/cys-take-on-pwc076.html
diff --git a/challenge-076/cheok-yin-fung/perl/ch-1.pl b/challenge-076/cheok-yin-fung/perl/ch-1.pl
new file mode 100644
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+++ b/challenge-076/cheok-yin-fung/perl/ch-1.pl
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+# Perl Weekly Challenge #076 Task 1 Prime Sum
+# task statement:
+# You are given a number $N. Write a script 
+# to find the minimum number of prime numbers 
+# required, whose summation gives you $N.
+# Usage: ch-1.pl $N
+
+# Given the Goldbach's conjecture is verified 
+# for n < 4 000 000 000 000 000 000 
+# ( source: mathworld.wolfram.com )
+
+use strict;
+use warnings;
+
+sub is_prime {
+    my $ans = 1; 
+    for my $i (2..int sqrt($_[0])) {
+        if ($_[0] % $i == 0) {$ans = 0; return 0;} 
+    } 
+    return $ans; 
+}
+
+my %oddprime;
+my $V;
+if ($ARGV[0]) {$V = $ARGV[0];} else {$V = 1024;}
+
+# small special cases
+
+if ($V == 1) {
+    print "0\nas 1 is smaller than the smallest prime.\n";
+    exit;
+}
+
+if ($V == 2) {
+    print "1\nas 2 is the smallest prime.\n";
+    exit;
+}
+
+if ($V == 4) {
+    print "2\nas 2 + 2 = 4 and 4 is not a prime.\n";
+    exit;
+}
+
+# normal cases
+sub setoddprime {
+    for my $p (3..$V) {$oddprime{$p} = 1 if is_prime($p);}
+}
+
+
+if ($V % 2 == 0) {
+    print "2\n";
+    setoddprime;
+    for (keys %oddprime) {
+        if ($oddprime{$V-$_}) {
+            print "as $_", " + ", $V-$_," = $V.\n" ;
+            last;
+        }
+    }
+} 
+else {
+    setoddprime;
+    if ($oddprime{$V}) {
+        print "1\nas $V is a prime.\n";
+    } 
+    elsif ($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 "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
new file mode 100644
index 0000000000..1642231842
--- /dev/null
+++ b/challenge-076/cheok-yin-fung/perl/ch-2.pl
@@ -0,0 +1,189 @@
+# 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;
+use warnings;
+use Data::Dumper;
+
+my @matrix;
+my @dictwords;
+my $gridfile;
+my $dictfile;
+
+if ($ARGV[1]) {
+    $gridfile = $ARGV[0];
+    $dictfile = $ARGV[1];
+} 
+else {
+    $gridfile = "pwc076grid";
+    $dictfile = "1000engwords.txt";
+}
+
+open GRID, $gridfile or die "no such text file for the grid: $gridfile";
+open DICT, $dictfile or die "no such text file for the dictionary: $dictfile";
+
+#read words from dictionary file
+foreach (<DICT>) {
+    my @temp;
+    if ($_ =~ /^[a-z]+$/) {
+        s/\s/\r/g;
+        s/\s//g;
+        push @temp, $_ ;
+    }
+    for my $line (@temp) {
+        push @dictwords, $line;
+    }
+}
+
+@dictwords = sort {$a cmp $b} @dictwords;
+
+# read the grid from grid file
+my $k = 0;
+for (<GRID>) {
+    chomp;
+    if ($_ ne "") {
+        @{$matrix[$k]} = split " ", $_;
+        $k++;
+    }
+}
+
+my $xlen = scalar @{$matrix[0]};
+my $ylen = scalar @matrix;
+
+# some subroutines for manipulating the lines on the grid 
+# ==============
+
+sub joinline {
+    return lc(join "", @_);
+}
+
+sub reversestring {
+    return join "", reverse (split //, $_[0]);
+}
+
+
+# horizontal and vertical lines
+# =============
+
+my @rowline, my @colline, my @urighttolleft;
+my @diagonal;
+
+for my $i (0..$ylen-1) { 
+    $rowline[$i*2] = joinline @{$matrix[$i]};
+    $rowline[$i*2+1] = joinline reverse @{$matrix[$i]};
+}
+
+for my $j (0..$xlen-1) {
+    $colline[$j*2] = joinline( map {${$matrix[$_]}[$j]} (0..$ylen-1) );
+    $colline[$j*2+1] = reversestring $colline[$j*2];
+}
+# ===========================
+
+
+# diagonal
+# ==============================
+sub find_diagonal {
+    my @mat = @{$_[0]};
+    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 $d (0..$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 $c (0..$t_diff) {
+            $ulefttolright[$c*2] = joinline  
+                map {${$mat[$_+$c]}[$_]} (0..$t_xlen-1) ; 
+            $ulefttolright[$c*2+1] = reversestring $ulefttolright[$c*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);
+}
+# =============================
+
+
+# antidiagonal
+# ==============================
+
+sub vertical_reflection {
+    my @mat = @{$_[0]};
+    my @newmat;
+    my $t_xlen = scalar @{$mat[0]};
+    my $t_ylen = scalar @mat;
+    for my $i (0..$t_ylen-1) {
+        @{$newmat[$i]} = ();
+        for my $j (0..$t_xlen-1) {
+            ${$newmat[$i]}[$j] = ${$mat[$i]}[-1-$j];
+        }
+    }
+    return @newmat;
+}
+
+
+@diagonal = find_diagonal(\@matrix);
+my @newmatrix = vertical_reflection(\@matrix) ;
+my @antidiagonal = find_diagonal( \@newmatrix);
+# ===========================
+
+
+# main dish:
+
+my %unique;
+
+for my $word (@dictwords) {
+    for (@rowline,@colline,@diagonal,@antidiagonal) {
+       if (defined $_) { 
+        if ($_ =~ /$word/ && not($unique{$word}) ) {
+            print $word, " ";
+            $unique{$word} = 1;
+        } 
+       }
+    }
+}
+
+print "\n";
+
+# grid: as given in task statement
+# 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	0m0.254s
+# user	0m0.249s
+# sys	0m0.004s
+