# Project Euler #234: Semidivisible numbers

# Project Euler #234: Semidivisible numbers

+ 4 comments I have solved this question but some testcases run correct where as some are Time Out. Is anyone solved this questions please guide me.

+ 0 comments I have implemented an efficient solution for the problem that can calculate the answer to the original euler project question (sum under 999966663333 answer not modular) however I'm struggling to compute the answer in the 10^18 range modulo 1004535809. The sieving I'm using is very efficient and the calculations are fast too, however sieving up to 10^9 will be pretty intensive even for the best sieves. Does anyone know about any resource on modular arithmetic that I could read to try and optimize the program by reducing the range using the module? Thanks

+ 0 comments Are there any edge cases here?

+ 0 comments this is my code in C#, I got just 8.22 can someone help.

using System; using System.Collections.Generic; using System.IO; class Solution { static void Main(String[] args) { /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */ // int l = int.Parse(Console.ReadLine()); // int r = int.Parse(Console.ReadLine());

`string[] lr = Console.ReadLine().Split(' '); long l = Convert.ToInt64(lr[0]); long r = Convert.ToInt64(lr[1]); long sum = 0; for (long number = l; number <= r; number++) { double lps = Math.Floor(Math.Sqrt(number)); double ups = Math.Ceiling(Math.Sqrt(number)); for (int i = 2; i < number / 2; i++) { if (i >= lps && lps > 2) { break; } if (lps % i == 0 && lps > 2) { lps--; i = 1; } } for (int i = 2; i < number / 2; i++) { if (i >= ups) { break; } if (ups % i == 0) { ups++; i = 1; } } if (number == (lps * lps)) { } else if (number % lps == 0 && number % ups == 0) { } else if (number % lps != 0 && number % ups != 0) { } else { sum = sum + number; } } Console.WriteLine(sum); Console.ReadLine(); }`

}

+ 0 comments how to convert string array value to long in c# as the given contraints say the limit of R will be 10^18.

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