Binary search and selection sort in Perl
* Create 01_binary_search.pl * Typo fixed in 01_binary_search.pl * Create 01_selection_sort.pl
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43
01_introduction_to_algorithms/perl5/01_binary_search.pl
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43
01_introduction_to_algorithms/perl5/01_binary_search.pl
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sub binary_search {
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my ( $item, @list ) = @_;
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# The borders inside where we are searching in:
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my $low = 0;
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my $high = $#list;
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# Do that until found or until just one element remains:
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while ( $low <= $high ) {
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# Detect the middle of the array:
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my $mid = int( ( $low + $high ) / 2 );
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my $guess = $list[$mid];
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# We found it out:
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if ( $guess == $item ) {
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return $mid;
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}
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# The guess is too high, decrease it:
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elsif ( $guess > $item ) {
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$high = --$mid;
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}
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# The guess is too low, increase it:
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else {
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$low = ++$mid;
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}
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}
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# Nothing at all found:
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return 'None';
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}
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my @my_list = qw /1 3 5 7 9/;
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# Should display "1":
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print binary_search( 3, @my_list ), "\n";
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# Should display "None":
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print binary_search( -1, @my_list ), "\n";
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32
02_selection_sort/perl5/01_selection_sort.pl
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02_selection_sort/perl5/01_selection_sort.pl
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# Detect the smallest value in an array
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sub findSmallest {
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my @arr = @_;
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my $smallest = $arr[0]; # Keep the smallest value
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my $smallest_index = 0; # Keep the index of the smallest value
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for ( my $i = 1; $i <= $#arr; $i++ ) {
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$smallest_index = $i if $arr[$i] < $smallest;
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}
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return $smallest_index;
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}
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# Sort array
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sub selectionSort {
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my @arr = @_;
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my @newArr = ();
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for ( 0 .. $#arr ) {
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my $smallest_index = findSmallest(@arr); # Find the smallest element in the array
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push @newArr, $arr[$smallest_index]; # Add it to the new array
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splice( @arr, $smallest_index, 1 ); # Delete that element
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}
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return @newArr;
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}
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print join( ' ', selectionSort( 5, 3, 6, 2, 10 ) ), "\n";
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