Peter
Peter Campbell Smith

Running persistence

Weekly challenge 238 — 9 October 2023

Week 238 - 9 Oct 2023

Task 1

Task — Running sum

You are given an array of integers. Write a script to return the running sum of the given array. The running sum can be calculated as sum[i] = num[0] + num[1] + …. + num[i].

Examples


Example 1
Input: @int = (1, 2, 3, 4, 5)
Output: (1, 3, 6, 10, 15)

Example 2
Input: @int = (1, 1, 1, 1, 1)
Output: (1, 2, 3, 4, 5)

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

Analysis

There's probably a one-liner for this, but I chose to do it in two. Note that by re-using the input @ints I didn't need to initialise the first member of the output array as it is the same as the input.

Try it 

Try running the script with any input, for example:
1, 2, 3, 4, 5


Script


#!/usr/bin/perl

use v5.16;    # The Weekly Challenge - 2023-10-09
use utf8;     # Week 237 task 1 - Running sum
use strict;   # Peter Campbell Smith
use warnings; # Blog: http://ccgi.campbellsmiths.force9.co.uk/challenge

running_sum(1, 2, 3, 4, 5);
running_sum(1, 1, 1, 1, 1);
running_sum(0, -1, 1, 2);
running_sum(34, 65, 12, -98, 87, 44, 72, 0, 39, 92);

sub running_sum {
    
    my (@ints, $j, @sums);
    
    @ints = @_;
    say qq[\nInput:  \@ints = (], join(', ', @ints) . ')';
    
    for $j (1 .. @ints - 1) {
        $ints[$j] = $ints[$j - 1] + $ints[$j];
    }
    
    say qq[Output:         (] . join(', ', @ints) . ')';
}
    

Output


Input:  @ints = (1, 2, 3, 4, 5)
Output:         (1, 3, 6, 10, 15)

Input:  @ints = (1, 1, 1, 1, 1)
Output:         (1, 2, 3, 4, 5)

Input:  @ints = (0, -1, 1, 2)
Output:         (0, -1, 0, 2)

Input:  @ints = (34, 65, 12, -98, 87, 44, 72, 0, 39, 92)
Output:         (34, 99, 111, 13, 100, 144, 216, 216, 255, 347)

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