diff options
| -rw-r--r-- | challenge-054/cheok-yin-fung/perl/ch-1.pl | 121 |
1 files changed, 62 insertions, 59 deletions
diff --git a/challenge-054/cheok-yin-fung/perl/ch-1.pl b/challenge-054/cheok-yin-fung/perl/ch-1.pl index a4caa6e5c4..b65e8d1fc5 100644 --- a/challenge-054/cheok-yin-fung/perl/ch-1.pl +++ b/challenge-054/cheok-yin-fung/perl/ch-1.pl @@ -4,8 +4,8 @@ use integer; sub knot {
- if ($_[0]) {$_[0] = 0;} else {$_[0] = 1};
- return $_[0];
+ if ($_[0]) {$_[0] = 0;} else {$_[0] = 1};
+ return $_[0];
}
if ($ARGV[0] == undef or $ARGV[1] == undef) {die "not enough arguments";}
@@ -26,12 +26,12 @@ my $n = 1; my @mobile = (); #store the indices
sub mmax { #modified from "Learning Perl", return the index of the largest char which in the status of mobile
- my @mchar = @char;
- my $champion = shift @_;
- foreach (@_) {
- if ( $mchar[$_] gt $mchar[$champion]) {$champion = $_;}
- }
- $champion;
+ my @mchar = @char;
+ my $champion = shift @_;
+ foreach (@_) {
+ if ( $mchar[$_] gt $mchar[$champion]) {$champion = $_;}
+ }
+ $champion;
}
@@ -40,57 +40,59 @@ for my $i (1..$P) {$noofperm *= $i;} push @result, join("", @char);
-while ( $n <= $noofperm-1 ) {
- my $j;
- @mobile = ();
- $j = 0; if ( ($char[$j] gt $char[$j+1]) and not($arrow[$j])) {
- push @mobile, $j;
- }
- for $j (1..$#char-1) {
- if ( ( $char[$j] gt $char[$j-1] and $arrow[$j]) or
- ( $char[$j] gt $char[$j+1] and not($arrow[$j])) ) {
- push @mobile, $j;
- }
- }
- $j = $#char; if ( $char[$j] gt $char[$j-1] and $arrow[$j]) {
- push @mobile, $j;
- }
-
-
- if ( $#mobile >= 0 ) {
- my $m = &mmax(@mobile);
- my $todaychamp; # a character
- my $arrowdirection; # a boolean
- if (not($arrow[$m])) {
- $todaychamp = $char[$m];
- $char[$m]=$char[$m+1];
- $char[$m+1] = $todaychamp;
- $arrowdirection = $arrow[$m];
- $arrow[$m] = $arrow[$m+1];
- $arrow[$m+1] = $arrowdirection;
- # then switch the direction of all the arrows above integers p with p>m
- foreach (0..$#char) {
- if ($char[$_] gt $todaychamp ) {
- $arrow[$_] = &knot($arrow[$_]);
- }
- }
- } else {
- $todaychamp = $char[$m];
- $char[$m]=$char[$m-1];
- $char[$m-1] = $todaychamp;
- $arrowdirection = $arrow[$m];
- $arrow[$m] = $arrow[$m-1];
- $arrow[$m-1] = $arrowdirection;
- foreach (0..$#char) {
- if ($char[$_] gt $todaychamp ) {
- $arrow[$_] = &knot($arrow[$_]);
- }
- }
- }
- }
- #switch the largest mobile integer m and the adjacent integer its arrow points to; the algorithms used here ref to "Introductory Combinatorics" 4th Edition by page 88, by Richard A. Brualdi
- push @result, join("", @char);
- $n++;
+while ( $n <= $noofperm-1 ) {
+ my $j;
+ @mobile = ();
+ $j = 0; if ( ($char[$j] gt $char[$j+1]) and not($arrow[$j])) {
+ push @mobile, $j;
+ }
+ for $j (1..$#char-1) {
+ if ( ( $char[$j] gt $char[$j-1] and $arrow[$j]) or
+ ( $char[$j] gt $char[$j+1] and not($arrow[$j])) ) {
+ push @mobile, $j;
+ }
+ }
+ $j = $#char; if ( $char[$j] gt $char[$j-1] and $arrow[$j]) {
+ push @mobile, $j;
+ }
+
+
+ if ( $#mobile >= 0 ) {
+ my $m = &mmax(@mobile);
+ my $todaychamp; # a character
+ my $arrowdirection; # a boolean
+ if (not($arrow[$m])) {
+ $todaychamp = $char[$m];
+ $char[$m]=$char[$m+1];
+ $char[$m+1] = $todaychamp;
+ $arrowdirection = $arrow[$m];
+ $arrow[$m] = $arrow[$m+1];
+ $arrow[$m+1] = $arrowdirection;
+ # then switch the direction of all the arrows above integers p with p>m
+ foreach (0..$#char) {
+ if ($char[$_] gt $todaychamp ) {
+ $arrow[$_] = &knot($arrow[$_]);
+ }
+ }
+ } else {
+ $todaychamp = $char[$m];
+ $char[$m]=$char[$m-1];
+ $char[$m-1] = $todaychamp;
+ $arrowdirection = $arrow[$m];
+ $arrow[$m] = $arrow[$m-1];
+ $arrow[$m-1] = $arrowdirection;
+ foreach (0..$#char) {
+ if ($char[$_] gt $todaychamp ) {
+ $arrow[$_] = &knot($arrow[$_]);
+ }
+ }
+ }
+ }
+ #switch the largest mobile integer m and the adjacent integer its arrow points to;
+ #the algorithms used here ref to
+ #"Introductory Combinatorics" 4th Edition by page 88, by Richard A. Brualdi
+ push @result, join("", @char);
+ $n++;
}
@@ -99,3 +101,4 @@ my @result = sort {$a <=> $b} @result; print $result[$k-1];
# Thanks for my worn combinatorics textbook again.
+# (wrote this as exercise long time ago)
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