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diff --git a/challenge-073/cheok-yin-fung/perl/ch-1a.pl b/challenge-073/cheok-yin-fung/perl/ch-1a.pl
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+#!/usr/bin/perl
+# Perl Weekly Challenge #073 Task 1 Sliding Windows
+# task statement:
+# You are given an array of integers @A and sliding window size $S.
+# Write a script to create an array of min from each sliding window.
+# Usage:  ch-1a.pl $S $A[0] $A[1]  ... $A[-1]
+# for large array size and large windows size , 
+# while $S is much smaller than size of the array though
+
+use strict;
+use warnings;
+#use Test::More tests => 7;
+
+my $S;
+my @A;
+
+sub choosemin {
+    my @array = @_;
+    my $min = $array[0];
+    my $minposition = 0;
+    for my $i (1..$#array) {
+        if ($array[$i] <= $min) {
+            $min = $array[$i];
+            $minposition = $i;
+        }
+    }
+    return [$min, $minposition]; 
+}
+
+sub awindows {
+    my $winsize = $_[0];
+    my @array = @{$_[1]};
+    my @smallkids = ();
+    my $min = undef;
+    my $minposition = undef;
+    
+    for my $winposition (0..$#array-$winsize+1) {
+        if ($min) {
+            my $i = $winsize - 1;
+            my $ele = $array[$winposition+$i]; 
+            if ($ele <= $min) {
+                $minposition = $i;
+                $min = $ele;
+            }
+        } else {
+            ($min, $minposition) 
+            = @{choosemin(@array[$winposition..$winposition+$winsize-1])};
+        }
+        push @smallkids, $min;
+        if ($minposition == 0) {
+            $min = undef;
+            $minposition = undef;
+        } else {
+            $minposition--;
+        }
+    }
+    return [@smallkids];
+}
+
+if ($ARGV[0] and $ARGV[1]) {
+    $S = shift @ARGV;
+    @A = @ARGV;
+} else {
+    $S = 7;
+    @A = qw/15 23 31 39 9 22 31 25 50 46 44 19 15 9 41 45 8 35 20 10/ ;
+}
+
+print join " ", @{ awindows($S, [@A])};
+print "\n";
+
+=pod
+is_deeply( awindows(3, [1, 5, 0, 2, 9,  3, 7, 6, 4, 8]), 
+    [0, 0, 0, 2, 3,  3, 4, 4], "example provided") ;
+is_deeply( awindows(3, [ 10, 47, 16, 50, 29,  21, 18, 20, 6, 30,  11]), 
+    [10, 16, 16, 21, 18,  18,  6 , 6,   6  ], "eleven random numbers");
+is_deeply( awindows(2, [2, 3, 5, 7, 11, 13, 17]), 
+    [2, 3, 5, 7, 11, 13], "ascending sequences");
+
+is_deeply( awindows(4, [reverse 1..10]),
+    [reverse 1..7], "descending first 10 positive integers");
+is_deeply( awindows(2, [qw/7 3 19 17 1 3 37 45 4 23 39 18 17 9 14
+                32 25 34 22 21 45 37 46 4 31 15 41 23 8 20/]),
+            [qw/3 3 17 1 1 3 37 4 4 23 18 17 9 9 14 25 25 
+                22 21 21 37 37 4 4 15 15 23 8 8/], 
+            "oh a long list, window size is 3");
+is_deeply( awindows(3, [qw/7 3 19 17 1 3 37 45 4 23 39 18 17 9 14
+                32 25 34 22 21 45 37 46 4 31 15 41 23 8 20/]),
+        [qw/3 3 1 1 1 3 4 4 4 18 17 9 9 9 14 25 22 21 21 21 37
+         4 4 4 15 15 8 8/], "a list same as above but window size is 3");
+is_deeply( awindows(7, [ qw/15 23 31 39 9 22 31 25 50 46 44
+            19 15 9 41 45 8 35 20 10/ ]), 
+        [qw/9 9 9 9 9 19 15 9 9 9 8 8 8 8/],
+        "a long list with 20 elements, with window size 7");
+=cut