project-euler/Sidef/125 Palindromic sums.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# Date: 25 July 2021
# https://github.com/trizen

# Find the sum of all the numbers less than 10^8 that are both palindromic and can be written as the sum of consecutive squares.

# https://projecteuler.net/problem=125

# Runtime: 4.334s

func p125(limit) {

    var s = limit.isqrt
    var sums = Set()

    for a in (1 .. s) {
        var sum = a.sqr
        for b in (a+1 .. s)  {
            sum += b.sqr
            #var sum = faulhaber_range(a, b, 2)
            break if (sum >= limit)
            sums << sum if sum.is_palindrome
        }
    }

    sums.sum
}

say p125(1e8)