백준 8393 합_JAVA

https://www.acmicpc.net/problem/8393

8393번: 합

n * ( n + 1 ) / 2 로도 계산가능

 

import java.util.Scanner;

public class Main{
       
   public static void main(String[] args) {
	   
	   Scanner sc = new Scanner(System.in);
		
	    int A = sc.nextInt();
	    
	    int sum =0 ;
	   
	    for (int i = 0 ; i <= A ; i++) {
	    	sum += i;
	    }
	    
	    System.out.println(sum);
  

	    sc.close();
    }
    
}