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+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+You have n teams in a tournament. A matrix grid tells you which team is stronger between any two teams:
+
+If grid[i][j] == 1, then team i is stronger than team j
+If grid[i][j] == 0, then team j is stronger than team i
+
+Find the champion team - the one with most wins, or if there is no single such team, the strongest of the teams with most wins. (You may assume that there is a definite answer.)
+
+Example 1
+
+Input: @grid = (
+                 [0, 1, 1],
+                 [0, 0, 1],
+                 [0, 0, 0],
+               )
+Output: Team 0
+
+[0, 1, 1] => Team 0 beats Team 1 and Team 2
+[0, 0, 1] => Team 1 beats Team 2
+[0, 0, 0] => Team 2 loses to all
+
+
+Example 2
+
+Input: @grid = (
+                 [0, 1, 0, 0],
+                 [0, 0, 0, 0],
+                 [1, 1, 0, 0],
+                 [1, 1, 1, 0],
+               )
+Output: Team 3
+
+[0, 1, 0, 0] => Team 0 beats only Team 1
+[0, 0, 0, 0] => Team 1 loses to all
+[1, 1, 0, 0] => Team 2 beats Team 0 and Team 1
+[1, 1, 1, 0] => Team 3 beats everyone
+
+
+Example 3
+
+Input: @grid = (
+                 [0, 1, 0, 1],
+                 [0, 0, 1, 1],
+                 [1, 0, 0, 0],
+                 [0, 0, 1, 0],
+               )
+Output: Team 0
+
+[0, 1, 0, 1] => Team 0 beats teams 1 and 3
+[0, 0, 1, 1] => Team 1 beats teams 2 and 3
+[1, 0, 0, 0] => Team 2 beats team 0
+[0, 0, 1, 0] => Team 3 beats team 2
+
+Of the teams with 2 wins, Team 0 beats team 1.
+
+
+Example 4
+
+Input: @grid = (
+                 [0, 1, 1],
+                 [0, 0, 0],
+                 [0, 1, 0],
+               )
+Output: Team 0
+
+[0, 1, 1] => Team 0 beats Team 1 and Team 2
+[0, 0, 0] => Team 1 loses to Team 2
+[0, 1, 0] => Team 2 beats Team 1 but loses to Team 0
+
+
+Example 5
+
+Input: @grid = (
+                 [0, 0, 0, 0, 0],
+                 [1, 0, 0, 0, 0],
+                 [1, 1, 0, 1, 1],
+                 [1, 1, 0, 0, 0],
+                 [1, 1, 0, 1, 0],
+               )
+Output: Team 2
+
+[0, 0, 0, 0, 0] => Team 0 loses to all
+[1, 0, 0, 0, 0] => Team 1 beats only Team 0
+[1, 1, 0, 1, 1] => Team 2 beats everyone except self
+[1, 1, 0, 0, 0] => Team 3 loses to Team 2
+[1, 1, 0, 1, 0] => Team 4 loses to Team 2
+
+=cut
+
+
+
+use List::Util qw(sum max);
+use Test2::V0 -no_srand => 1;
+is(champion_team([0, 1, 1], 
+                 [0, 0, 1], 
+                 [0, 0, 0]), 0, 'Example 1');
+is(champion_team([0, 1, 0, 0],
+                 [0, 0, 0, 0],
+                 [1, 1, 0, 0],
+                 [1, 1, 1, 0]), 3, 'Example 2');
+
+is(champion_team([0, 1, 0, 1],
+                 [0, 0, 1, 1],
+                 [1, 0, 0, 0],
+                 [0, 0, 1, 0]), 0, 'Example 3');
+is(champion_team([0, 1, 1],
+                 [0, 0, 0],
+                 [0, 1, 0]), 0, 'Example 4');
+is(champion_team([0, 0, 0, 0, 0],
+                 [1, 0, 0, 0, 0],
+                 [1, 1, 0, 1, 1],
+                 [1, 1, 0, 0, 0],
+                 [1, 1, 0, 1, 0]), 2, 'Example 5');                 
+                 
+done_testing();
+
+
+sub champion_team
+{
+     my @grid = @_;
+     my %results;
+     for my $i ( 0 .. $#grid )
+     {
+          my $sum = sum(@{$grid[$i]});
+          $results{$i} = $sum;
+     }
+     my $max = max(values %results); 
+     my @tied = grep { $results{$_} == $max } keys %results; 
+     if ( scalar(@tied) == 1 ) { return $tied[0];}
+     
+     my %results_tied;
+     for my $first ( @tied )
+     {
+          for my $second ( @tied )
+          {
+               $results_tied{$first} += $grid[$first][$second];
+          }
+     }
+     my $max_tied = max( values %results_tied ); 
+     my @wins = grep { $results_tied{$_} == $max_tied } keys %results_tied;
+     return wantarray ? @wins : "@wins"; # tied is still possible.
+}