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+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+You are given an array of integers, @ints.
+Find all the peaks in the array, a peak is an element that is strictly greater than its left and right neighbours. Return the indices of all such peak positions.
+
+Example 1
+
+Input: @ints = (1, 3, 2)
+Output: (1)
+
+
+Example 2
+
+Input: @ints = (2, 4, 6, 5, 3)
+Output: (2)
+
+
+Example 3
+
+Input: @ints = (1, 2, 3, 2, 4, 1)
+Output: (2, 4)
+
+
+Example 4
+
+Input: @ints = (5, 3, 1)
+Output: (0)
+
+
+Example 5
+
+Input: @ints = (1, 5, 1, 5, 1, 5, 1)
+Output: (1, 3, 5)
+
+=cut
+
+
+use Test2::V0 -no_srand => 1;
+
+is([peak_positions(1, 3, 2)], [1], 'Example 1');
+is([peak_positions(2, 4, 6, 5, 3)], [2], 'Example 2');
+is([peak_positions(1, 2, 3, 2, 4, 1)], [2, 4], 'Example 3');
+is([peak_positions(5, 3, 1)], [0], 'Example 4');
+is([peak_positions(1, 5, 1, 5, 1, 5, 1)], [1, 3, 5], 'Example 5');
+done_testing();
+
+sub peak_positions
+{
+     my @arr = @_;
+     if ( scalar(@arr) == 1) { return 0; } 
+     my @positions;
+     for my $idx ( 0 .. $#arr )
+     {
+          if ( 
+               ($idx == 0 and $arr[$idx] > $arr[$idx+1]) or 
+               ($idx < $#arr  and $arr[$idx] > $arr[$idx-1] 
+                              and $arr[$idx] > $arr[$idx+1]) or
+               ($idx == $#arr and $arr[$idx] > $arr[$idx-1])
+          )
+          {
+               push @positions, $idx;
+          }
+     }
+     return @positions;
+}