Task — Peak point

You are given an array of altitude gain. Write a script to find the peak point gained.

Examples

Example 1
Input: @gain = (-5, 1, 5, -9, 2)
Output: 1
start: 0
1st change:  0 + (-5) = -5
2nd change: -5 + 1    = -4
3rd change: -4 + 5    = 1
4th change:  1 + (-9) = -8
5th change: -8 + 2    = -6
max(0, -5, -4, 1, -8, -6) = 1

Example 2
Input: @gain = (10, 10, 10, -25)
Output: 30

Example 3
Input: @gain = (3, -4, 2, 5, -6, 1)
Output: 6

Example 4
Input: @gain = (-1, -2, -3, -4)
Output: 0

Example 5
Input: @gain = (-10, 15, 5)
Output: 10

Analysis

This is another task which can probably be reduced to a one-liner, but I have done it more transparently by repeatedly adding (or subtracting) the steps from a starting point of zero.

This is related to the statistical problem known as the drunkard's walk.

Try it 

#!/usr/bin/perl

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

use v5.26;    # The Weekly Challenge - 2025-09-15
use utf8;     # Week 339 - task 2 - Peak point
use warnings; # Peter Campbell Smith
binmode STDOUT, ':utf8';
use Encode;

peak_point(-5, 1, 5, -9, 2);
peak_point(10, 10, 10, -25);
peak_point(3, -4, 2, 5, -6, 1);
peak_point(-1, -2, -3, -4);
peak_point(-10, 15, 5);

my @steps;
push @steps, int(rand(21)) - 10 for 1 .. 100; 
peak_point(@steps);

sub peak_point {
    
    my ($height, $highest, $climb);
    
    # initialise
    $height = 0;
    $highest = 0;
    
    # start climbing
    for $climb (@_) {
        $height += $climb;
        $highest = $height if $height > $highest;
    }
    
    say qq[\nInput:  (] . join(', ', @_) . ')';
    say qq[Output: $highest];
}

Output

Input:  (-5, 1, 5, -9, 2)
Output: 1

Input:  (10, 10, 10, -25)
Output: 30

Input:  (3, -4, 2, 5, -6, 1)
Output: 6

Input:  (-1, -2, -3, -4)
Output: 0

Input:  (-10, 15, 5)
Output: 10

Input:  (7, 10, -5, 6, 8, -7, 5, -7, 1, -3, -10, 2, 2, -4,
   -3, -2, -9, -4, 8, -5, 10, -10, -6, 5, -1, -8, -8, 1,
   -5, -5, -8, -5, -2, 8, -8, -2, -2, 3, -9, -9, -8, -3,
   6, -4, -6, -7, 8, 4, 6, -1, -8, 6, 7, -1, -2, 7, -1, 1,
   -6, -3, 6, -4, -3, -2, -6, -6, 8, 1, -4, 1, -5, 0, 6,
   2, 4, 5, 1, -7, -9, -7, -3, -3, 10, 3, 7, 0, 7, -8, -1,
   -1, 5, -4, -8, 10, -1, -3, -6, 9, -10, 8)
Output: 26