Submission #2124025

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Source Code Expand

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ABC084D {
    class Program {
        static void Main(string[] args) {
            bool[] primes = Enumerable.Repeat(true, 100001).ToArray();
            primes[0] = false;
            primes[1] = false;
            for (int i = 2; i < 100001; i++) {
                if (primes[i]) {
                    int num = i * 2;
                    while(num < 100001) {
                        primes[num] = false;
                        num += i;
                    }
                }
            }
            int Q = int.Parse(Console.ReadLine());
            for(int i = 0; i < Q; i++) {
                int[] input = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
                int l = input[0];
                int r = input[1];
                int ans = 0;
                for(int j = l; j <= r; j += 2) {
                    if (primes[j] && primes[(j + 1)/2]) {
                        ans++;
                    }
                }
                Console.WriteLine(ans);
            }
        }
    }
}

Submission Info

Judge Result