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.

Try it 

#!/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