project-euler/Julia/125 Palindromic sums.jl

#!/usr/bin/julia

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

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

# Runtime: 3.127s

@inline function is_csquare(n::Int64)
    s = isqrt(n)
    for i in 1:s-1
        sum = i^2
        for j in i+1:s
            sum += j^2
            sum > n && break
            sum == n && return true
        end
    end
    return false
end

function count_sum(limit::Int64)

    sum = 0

    for i in 1:9
        if is_csquare(i)
            sum += i
        end
    end

    i = 1
    while true
        s = string(i)
        r = reverse(s)
        p = s * r
        k = parse(Int64, p)
        k >= limit && break

        if is_csquare(k)
            sum += k
        end

        for j in 0:9
            p = s * string(j) * r
            k = parse(Int64, p)
            k >= limit && break
            if is_csquare(k)
                sum += k
            end
        end
        i += 1
    end
    return sum
end

println(count_sum(100000000))