project-euler/Sidef/076 Counting summations.sf

#!/usr/bin/ruby

# Author: Daniel "Trizen" Șuteu
# License: GPLv3
# Website: https://github.com/trizen

# How many different ways can one hundred be written as a sum of at least two positive integers?

# https://projecteuler.net/problem=76

# Runtime: 0.626s

var nums = []

func count(n, i=0, sum=0) is cached {
    return 1 if (sum == n)
    return 0 if (sum > n)
    return 0 if (i > nums.end)

    count(n, i+1, sum) +
    count(n, i, sum + nums[i])
}

var n = 100
nums = @(1 ..^ n)

say count(100)