hdu1001

//c #include "stdio.h" int main() { int a = 0, sum = 0; while (scanf("%d", & a) != EOF) { if ((a << 31) >> 31 == 0) { sum = a / 2; sum *= a + 1; printf("%d\n\n", sum); } else { sum = (a + 1) / 2; sum *= a; printf("%d\n\n", sum); } } return 0; }

//c++ #include "iostream" using namespace std; int main() { int a = 0, sum = 0; while (cin >> a) { if ((a << 31) >> 31 == 0) { sum = a / 2; sum *= a + 1; cout << sum << endl; cout << endl; } else { sum = (a + 1) / 2; sum *= a; cout << sum << endl; cout << endl; } } return 0; }

//c# using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace csharp { class Program { static void Main(string[] args) { string s; int a, sum; while ((s = Console.ReadLine()) != null) { a = Convert.ToInt32(s); if ((a << 31) >> 31 == 0) { sum = a / 2; sum *= a + 1; Console.WriteLine("{0}\n\n", sum); } else { sum = (a + 1) / 2; sum *= a; Console.WriteLine("{0}\n\n", sum); } } } } }

//java import java.util.Scanner; public class Main { public static void main(String args[]) { Scanner s = new Scanner(System. in ); while (s.hasNextInt()) { int n = s.nextInt(); if ((n << 31) >> 31 == 0) { int sum = n / 2; sum = sum * (n + 1); System.out.println(sum); System.out.println(); } else { int sum = (n + 1) / 2; sum = sum * n; System.out.println(sum); System.out.println(); } } } }