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+#!/usr/env/perl
+# Task 1 Challenge 048 Solution by saiftynet
+# 
+# Survivor
+# 
+# There are 50 people standing in a circle in position 1 to 50. The person 
+# standing at position 1 has a sword. He kills the next person i.e. standing 
+# at position 2 and pass on the sword to the immediate next i.e. person standing 
+# at position 3. Now the person at position 3 does the same and it goes on 
+# until only one survives.
+# 
+# Write a script to find out the survivor.
+# 
+# Probably the best way to implement a circular list is to shift an element
+# and then push it back on the ther end...s the whole array rotates, and
+# our index remain in the same position, rather than to have a pointer
+# that is checked to see if it has reached the boundary every time and 
+# reset to end or start depending on which way we moving the pointer.
+#
+# For the purposes of this task, we will have the sword holder at position 0
+# the victime is at postion 1, and the sword receiver is at position 2.
+#
+# For a bit of fun, an attempt is made at animating this.  This works on
+# an 80x24 console that supports `cls` in Windows or `clear` in Linux
+# or OSX
+
+
+my @circleList=(1..50);
+
+# clear screen can be done using Term::XXX, but in case the module is
+# not accessible, I have adapted an answer from
+# https://stackoverflow.com/questions/197933
+
+my $clearScreen=( $^O=~/Win/)?`cls`:`clear`;
+
+my $animate=1;       # set this to 0 if you dont want to animate.
+ 
+while (scalar @circleList >1){
+  if ($animate){     # animation is optional; may not work or be desired
+	 select(undef, undef, undef, 0.25); 
+	 print $clearScreen;
+     circle(\@circleList);
+  }
+  else{
+	   print join ",",@circleList;
+  }
+  my $killer=shift @circleList;    # get the killer, ready to push to end
+  my $killed=shift @circleList;    # get the killed and dump it
+  push @circleList,$killer;        # push killer to end of list
+  print "\n$killer killed $killed".# display results
+        ( (scalar @circleList > 1)?
+           " and passed sword to $circleList[0]\n":
+           " and is last man standing!!\n");
+  
+}
+
+# subroutine to plot a circular list in a circle. 
+sub circle{  
+	my $circleList=shift;         
+	my @plotArea   = ();          # reset plot area
+    push @plotArea, [("  ") x 40,"\n"]
+         foreach (0..16);         # two spaces per point
+     
+    my $center=[9,20];            # adjust for different console sizes
+    my $radius=[8,18];            # adjust for different console sizes
+     foreach my $angle (0..@$circleList-1){
+       $plotArea [$$center[0]+$$radius[0]*sin($angle*6.28/@$circleList)]
+                 [$$center[1]-$$radius[1]*cos($angle*6.28/@$circleList)]
+                 =$$circleList[$angle];       
+     }
+         print @{$_} foreach (@plotArea); # the plot area
+}