투 포인터

이동원칙

1. sum>N
	sum=sum-start_index, start_index++
2. sum<N
	end_index++, sum=sum+end_index
3. sum=N
    end_index++, sum=sum+index, count++
         

백준2018

package baekjoon;
import java.util.Scanner;
public class Baekjoon2018 {

	public static void main(String[] args) {
		
		Scanner input = new Scanner(System.in);
		int N = input.nextInt();
		
		int count=1, sum=1;
		int start_index=1, end_index=1;
				
		while(N!=end_index) {
			if(sum>N) {
				sum=sum-start_index;
				start_index++;
			}
			else if(sum==N) {
				end_index++;
				sum=sum+end_index;
				count++;
			}
			else {
				end_index++;
				sum=sum+end_index;
				
			}
		}
		System.out.println(count);
	}	

}