allow a small cheat: blog not yet finish

3 files changed, 486 insertions, 0 deletions

diff --git a/challenge-086/cheok-yin-fung/blog.txt b/challenge-086/cheok-yin-fung/blog.txt
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+++ b/challenge-086/cheok-yin-fung/blog.txt
@@ -0,0 +1 @@
+http://blogs.perl.org/users/c_y_fung/2020/11/sudoku.html
diff --git a/challenge-086/cheok-yin-fung/perl/ch-1.pl b/challenge-086/cheok-yin-fung/perl/ch-1.pl
new file mode 100644
index 0000000000..a1d0e7c378
--- /dev/null
+++ b/challenge-086/cheok-yin-fung/perl/ch-1.pl
@@ -0,0 +1,59 @@
+#!/usr/bin/perl
+# The Weekly Challenge - Perl & Raku - 086
+# Task: Pair Difference 
+
+use strict;
+use warnings;
+# use Test::More tests => 3;
+
+pair_diff(@ARGV) if $ARGV[0];
+
+sub pair_diff {
+
+    my $dff = shift @_;
+    my @arr = sort {$a <=> $b} @_;
+
+
+
+    if ($dff < 0) {
+        $dff = -$dff;
+    }
+
+    my @newarr = map { $arr[$_+1] - $arr[$_] } (0..$#arr-1);
+
+
+    my $bool = 1;
+    for my $e (@newarr) {
+        $bool = $bool && $dff < $e;
+        if ($dff == $e) {
+            print 1,"\n";
+            return 1;
+        }
+    }
+
+    if ($bool) {
+        print "The difference required may be too small.\n"; 
+        print 0,"\n"; 
+        return 0;
+    }
+
+    for my $i (0..$#arr-1) {
+        for my $j ($i+1..$#arr) {
+            if ($dff == $arr[$j]-$arr[$i]) {
+                print 1,"\n";
+                return 1;
+            }
+        }
+    }
+
+    print 0,"\n";
+    return 0;
+
+}
+
+
+=pod
+ok pair_diff(7, 10, 8, 12, 15, 5) == 1, "example 1";
+ok pair_diff(6, 1, 5, 2, 9, 7) == 1, "example 2";
+ok pair_diff(15, 10, 30, 20, 50, 40) == 0, "example 3";
+=cut
diff --git a/challenge-086/cheok-yin-fung/perl/ch-2.pl b/challenge-086/cheok-yin-fung/perl/ch-2.pl
new file mode 100644
index 0000000000..865deee74b
--- /dev/null
+++ b/challenge-086/cheok-yin-fung/perl/ch-2.pl
@@ -0,0 +1,426 @@
+#!/usr/bin/perl
+# The Weekly Challenge - Perl & Raku - 086
+# Task: Sudoku
+# print one of the possible solutions for the given hints
+# print -1 if impossible
+# Usage: capable for generating 16 x 16 Sudoku SOMETIMES,  try: perl ch-2.pl 4
+# capable for generating 25 x 25 Sudoku in very FEW cases, try: perl ch-2.pl 5
+# Caution: The part for declaring impossibility hasn't been tested.
+# Caution: The subroutine "come_bk_after_fail_attempt" 
+#          is not logically complete 
+# version date: 2020-11-15 HKT afternoon
+
+use strict;
+use warnings;
+
+my @tree;
+my @board;
+
+my $LEVEL = $ARGV[0] ? $ARGV[0] : 3;  #default value of board length: 3*3=9
+my $BSIZE = $LEVEL**4;
+my $E_LEN = $LEVEL**2;
+my @ABT = ('A'..chr(ord('A')+$E_LEN-1));
+&initialize;
+
+# TESTING INPUT, from example provided
+if (!$ARGV[0]) {
+@board = split "", "zzzBFzGzAFHzzGzzIzAIzzzDEzzHBzAzzzDzzzDFzBIzzzEzzzCzBHzzICzzzGDzDzzEzzCFGzCzAHzzz";
+}
+
+my $BITWORLD = 2**($E_LEN+1)-1;
+
+my %bit_repr;
+for my $i (0..$E_LEN-1) {
+    $bit_repr{$ABT[$i]} = 2**$i;
+}
+
+{package node;
+use strict;
+
+sub new
+{
+    my ($class) = @_;
+    bless{
+        _position => $_[1],
+        _value => $_[2],
+        _is_stable => $_[3],
+        _depth => $_[4],
+        _nexts => $_[5],   #list of references to nodes
+    }, $class;
+
+
+}
+
+    sub position {return $_[0]->{_position};}
+    sub value {return $_[0]->{_value};}
+    sub is_stable {return $_[0]->{_is_stable};}
+    sub depth {return $_[0]->{_depth};}
+    sub nexts {return $_[0]->{_nexts};}
+    
+1;
+}
+
+# ==== representation
+
+sub num_repr {
+    return (ord($board[$_[0]])-ord("A"));
+}
+
+sub internal_repr_to_trad_3 {
+    for my $i (0..$E_LEN-1) {
+        for my $j (0..$E_LEN-1) {
+            my $p = $i*$E_LEN+$j;
+            if ($board[$p] ne "z") {
+                print ord($board[$i*$E_LEN+$j])-ord("A")+1, " ";
+            } else
+            {
+                print "_ ";
+            }
+        }
+        print "\n";
+    }
+}
+
+sub internal_repr_to_trad {
+    for my $i (0..$E_LEN-1) {
+        for my $j (0..$E_LEN-1) {
+            my $p = $i*$E_LEN+$j;
+            if ($board[$p] ne "z") {
+                print $board[$i*$E_LEN+$j], " ";
+            } else
+            {
+                print "_ ";
+            }
+        }
+        print "\n";
+    }
+}
+
+sub TEST_print_board {
+    for my $i (0..$E_LEN-1) {
+        for my $j (0..$E_LEN-1) {
+            print $board[$i*$E_LEN+$j], " ";
+        }
+        print "\n";
+    }
+}
+
+sub coord_to_nth_row {return int( $_[0] / $E_LEN );}
+sub coord_to_nth_col {return $_[0] % $E_LEN;}
+sub coord_to_nth_ssq {
+    my $r = coord_to_nth_row($_[0]);
+    my $c = coord_to_nth_col($_[0]);
+    return ( (int ($r / $LEVEL)) *$LEVEL + int($c / $LEVEL)  ) ;
+}
+# +-+-+-+
+# |0|1|2|  012
+# +-+-+-+
+# |3|4|5|  345
+# +-+-++
+# |6|7|8|  678
+# +-+-+-+
+
+# ==== begin checking lines
+
+sub checkrows {
+    my @rown = @_;
+    my $bool = 1;
+    foreach my $r (@rown) {
+        my $nvalue = 0;
+        my $zcount = 0;
+        for my $p ($E_LEN*$r..$E_LEN*$r+$E_LEN-1) {
+            my $alpha = $board[$p];
+            if ($alpha != "z") {
+                if ( ($bit_repr{$alpha} & $nvalue) > 0) {  #repeat appearance
+                    return undef;
+                }
+                $nvalue += $bit_repr{$alpha};
+            } else 
+            {
+                $zcount++;
+            }
+        }
+        if ($zcount == 0 and $nvalue == 0) {
+            return undef;
+        }
+    }
+
+    return $bool;
+}
+
+sub checkcols {
+    my @coln = @_;
+    my $bool = 1;
+    for my $c (@coln) {
+        my $nvalue = 0;
+        my $zcount = 0;
+        for my $p (0..$E_LEN-1) {
+            my $alpha = $board[$E_LEN*$p+$c];
+            if ($alpha != "z") {
+                if ( ($bit_repr{$alpha} & $nvalue) > 0) {  #repeat appearance
+                    return undef;
+                }
+                $nvalue += $bit_repr{$alpha};
+            } else 
+            {
+                $zcount++;
+            }
+        }
+        if ($zcount == 0 and $nvalue == 0) {
+            return undef;
+        }
+    }
+    return $bool;
+}
+
+
+sub r_ssq_tl {
+    my $ssq_id = $_[0];
+    my $floor = (int ($ssq_id / $LEVEL));
+    return $LEVEL*($ssq_id % $LEVEL + $floor*$E_LEN);
+}
+
+sub checkssqs {
+    my @ssqn = @_;
+    my $bool = 1;
+    foreach my $sq (@ssqn) {
+        my $nvalue = 0;
+        my $zcount = 0;
+        my $ssq_tl = r_ssq_tl($sq);
+        for my $p ( 0..$LEVEL-1 ) {     
+            for my $q (0..$LEVEL-1) {
+                my $alpha = $board[$ssq_tl+$p+$q*$E_LEN]; 
+                if ($alpha != "z") {
+                    if ( ($bit_repr{$alpha} & $nvalue) > 0) {  #repeat appearance
+                        return undef;
+                    }
+                    $nvalue += $bit_repr{$alpha};
+                } else 
+                {
+                    $zcount++;
+                }
+        }}
+        if ($zcount == 0 and $nvalue == 0) {
+            return undef;
+        }
+    }
+    return $bool;
+}
+
+
+# ==== end of checking lines
+
+# ==== algorithmic stuff
+
+
+
+sub come_bk_from_fail_attempt {
+    die "Too much recursion" if $#tree > 5001;  #appear when $LEVEL > 3
+    my $naughty = pop @tree;
+
+    # print "$#tree\n";      this line is for testing
+    if (!($naughty)) {
+        print "here";
+        &declare_impossibility;
+    }
+
+    # act on the board to return the board to a proper value
+
+    if (defined($naughty->nexts)) {
+        # pop @{$naughty->nexts};   #seem no difference? 
+        $board[$naughty->position] = 'z';
+
+        die "TRY AGAIN" if $#tree == -1;
+
+        my $leaf = \($tree[$#tree]);
+
+        if (!($$leaf->nexts) && $$leaf->is_stable) {
+                print "here";
+                &declare_impossibility;
+        }
+
+         if ($naughty->depth == $$leaf->depth+1) {
+            if (!($$leaf->nexts) && $$leaf->is_stable) {
+                print "there";
+                &declare_impossibility;
+            }
+             
+        }
+        if (scalar @{$$leaf->nexts} <= 1) {
+            #  print "======================= need here\n"; #Testing lines
+            my $active = pop @tree;
+            $board[$active->position] = 'z';
+            &come_bk_from_fail_attempt;
+        }
+    } else {
+        print "zere"; 
+        &declare_impossibility;
+    }
+}
+
+sub declare_impossibility {
+    TEST_print_board;
+    die "-1\nImpossible arrangement!";
+}
+
+sub check_complete {
+    if (countz() == 0) {
+        # can add checking lines here
+        return 1;
+    }
+    return undef;  
+}
+
+sub action_on_new_node {
+    my $leaf = \$tree[$#tree];
+    #  print "tree id: $#tree   pos: ", $$leaf->position; 
+    #  print " val:", $$leaf->value , "\n"; 
+    # the above printing is for various testings 
+    if (defined($$leaf) && defined($$leaf->position)) {
+        $board[$$leaf->position] = $$leaf->value;
+        
+        my $pos = &choose_an_empty_entry;
+        my $p_value = choose_possible_values_for_entry($pos) if defined($pos);
+        if (defined($pos) && @{$p_value} ) {
+            for my $v (@{$p_value}) {  
+                push @{$$leaf->nexts}, 
+                    node->new($pos, $v, 0, ($$leaf->depth)+1, []);
+            }
+            # push @tree, reverse @{$$leaf->nexts};
+            # my $trial = shift @{$$leaf->nexts};
+            # push @tree, $trial;
+            
+             my $trial = shift @{$$leaf->nexts};
+             push @tree, @{$$leaf->nexts};
+             push @tree, $trial;
+        } else
+        { if (!check_complete()) {
+                # print "location A \n";    #TESTING LINES
+                come_bk_from_fail_attempt;
+            }
+        }
+    } else 
+    {
+        # print "location B \n";
+        come_bk_from_fail_attempt;
+    }
+}
+
+
+sub bitstr_to_set_of_alphabets {
+    my $bitstr = $_[0];
+    my @set = ();
+    for my $p (0..$E_LEN-1) {
+        my $temp = 2**$p;
+        if ($temp & $bitstr) {
+            push @set, $ABT[$p];
+        }
+    }
+    return \@set;
+}
+
+sub choose_an_empty_entry {
+    my @emptyentry_pos;
+    for my $i (0..$BSIZE-1) { push @emptyentry_pos,$i if $board[$i] eq 'z';}
+    
+    my $min_opp = $E_LEN;
+    my @candidate_small;
+    for my $i (@emptyentry_pos) {
+        my $temp_i = scalar @{choose_possible_values_for_entry($i)} ;
+        if ($temp_i < $min_opp) {
+            $min_opp = $temp_i;
+            @candidate_small = ($i)
+        } elsif ( $temp_i == $min_opp ) 
+        {
+            push @candidate_small, $i;
+        }
+    }
+    
+    @candidate_small = random_an_array(@candidate_small);
+    return $candidate_small[0];
+}
+
+sub choose_possible_values_for_entry {
+    my $e = $_[0];
+
+    my $impos_set = 0;
+
+    #rows
+    for (0..$E_LEN-1)
+    {
+        my $coo = $E_LEN*coord_to_nth_row($e) + $_;
+        $impos_set = $impos_set | 2**num_repr($coo) if $board[$coo] ne 'z';
+    }   
+
+    #columns
+    for (0..$E_LEN-1) {
+        my $coo = coord_to_nth_col($e) + $_*$E_LEN;
+        $impos_set = $impos_set | 2**num_repr($coo) if $board[$coo] ne 'z';
+    }
+    
+    #small squares
+    my $sq_e = (int ($e / $LEVEL) % $LEVEL) + $LEVEL * int ($e / $LEVEL / $E_LEN ); 
+    for my $p (0..$LEVEL-1) {
+        for my $q (0..$LEVEL-1) {
+             my $coo = r_ssq_tl($sq_e) + $p + $q*$E_LEN;
+             $impos_set = $impos_set | 2**num_repr($coo) if $board[$coo] ne 'z';
+        }
+    }
+    
+    my $bit_opp = ( ~ $impos_set ) & $BITWORLD;
+    return [@{bitstr_to_set_of_alphabets($bit_opp)}];
+}
+
+
+sub random_an_array {
+    my $size = scalar @_;
+    my @original = @_;
+    my %assist = ();
+    my @arrangement;
+    for (@original) {
+       $assist{$_} = int(1 + rand $size);
+    }
+    @arrangement = sort { $assist{$a} <=> $assist{$b}} (keys %assist);
+    return @arrangement;
+}
+
+sub countz {
+    my $ans = 0;
+    for my $p (0..$BSIZE-1) {
+        $ans++ if $board[$p] eq "z" ;
+    }
+    return $ans;
+}
+
+# ===== all procedural stuffs are coming!
+
+#*** heart of this script ***************
+sub main {
+    my $o = &choose_an_empty_entry;
+    $tree[0] = node->new($o, 'z', 1, 0, [] ); #create tree root
+
+    for my $v (@{choose_possible_values_for_entry($o)}) {
+       push @tree, 
+           node->new($o, $v, 0, 1, []); 
+    }
+    while ( &countz > 0) { 
+        action_on_new_node;
+    }
+    if (check_complete) {
+        internal_repr_to_trad_3 if $LEVEL == 3; 
+        internal_repr_to_trad if $LEVEL >= 4; 
+        print "\n"; 
+        # &initialize;  # next round?
+        exit;
+    };
+}
+
+sub initialize {
+    @board = ('z') x $BSIZE;
+    @tree = (); #Depth-first search, a stack of nodes
+}
+
+# for my $t (1..1000) {main(); print $t,"\n";}
+# the above is a line for testing 9x9 sudoku
+
+main();