Highest row

You are given an $m x $n matrix. Write a script to find the highest row sum in the given matrix.

Examples

Example 1
Input: @matrix = ([4,  4, 4, 4],
                  [10, 0, 0, 0],
                  [2,  2, 2, 9])
Output: 16
Row 1: 4  + 4 + 4 + 4 => 16
Row 2: 10 + 0 + 0 + 0 => 10
Row 3: 2  + 2 + 2 + 9 => 15

Example 2
Input: @matrix = ([1, 5],
                  [7, 3],
                  [3, 5])
Output: 10

Example 3
Input: @matrix = ([1, 2, 3],
                  [3, 2, 1])
Output: 6

Example 4
Input: @matrix = ([2, 8, 7],
                  [7, 1, 3],
                  [1, 9, 5])
Output: 17

Example 5
Input: @matrix = ([10, 20,  30],
                  [5,  5,   5],
                  [0,  100, 0],
                  [25, 25,  25])
Output: 100

Analysis

This is a challenge where there will be a one-liner which is not straightforward to decipher, and as usual I have gone for a more verbose, but more transparent solution.

Peter's solutions are exemplary models of clarity, robustness and efficiency. He deliberately chooses transparent, verbose code over clever one-liners, making his solutions easy to understand and maintain. Furthermore, he demonstrates deep insight by identifying and implementing highly efficient algorithms, especially for the second task.

This review may cover either or both challenges for this week.

Try it 

Try running the script with any input:

Your @matrix =

example: [1, 7, 11], [4, 8, 6], [9, 2, 9]

⤡

#!/usr/bin/perl

# Blog: http://ccgi.campbellsmiths.force9.co.uk/challenge

use v5.26;    # The Weekly Challenge - 2025-09-08
use utf8;     # Week 338 - task 1 - Highest row
use warnings; # Peter Campbell Smith
binmode STDOUT, ':utf8';
use Encode;

highest_row([4, 4, 4, 4], [10, 0, 0, 0], [2,  2, 2, 9]);
highest_row([1, 5], [7, 3], [3, 5]);
highest_row([1, 2, 3], [3, 2, 1]);
highest_row([10, 20,  30], [5,  5,   5], [0,  100, 0], [25, 25,  25]);
highest_row([-1, -2, -3], [-4, -5, -6], [-7, -8, -9]);

sub highest_row {
    
    my (@matrix, $highest, $row_sum, $row);
    
    # initialise
    @matrix = @_;
    $highest = -Inf;
    
    # find row sums
    for $row (0 .. scalar @matrix - 1) {
        $row_sum = 0;
        $row_sum += $_ for @{$matrix[$row]};
        $highest = $row_sum if $row_sum > $highest;
    }
    
    # report
    say '';
    print_matrix(qq[Input: ], \@matrix);
    say qq[Output: $highest];
}

sub print_matrix {
    
    my ($legend, $matrix, $j);

    # format matrix
    ($legend, $matrix) = @_;
    for $j (0 .. @$matrix - 1) {
        print qq{$legend [} . join(', ', @{$matrix->[$j]}) . qq(]);
        say $j == @$matrix - 1 ? '' : ', ';
        $legend = ' ' x length($legend);
    }
}

18 lines of code

Output from script

Input:  [4, 4, 4, 4], 
        [10, 0, 0, 0], 
        [2, 2, 2, 9]
Output: 16

Input:  [1, 5], 
        [7, 3], 
        [3, 5]
Output: 10

Input:  [1, 2, 3], 
        [3, 2, 1]
Output: 6

Input:  [10, 20, 30], 
        [5, 5, 5], 
        [0, 100, 0], 
        [25, 25, 25]
Output: 100

Input:  [-1, -2, -3], 
        [-4, -5, -6], 
        [-7, -8, -9]
Output: -6