백준 JAVA 3273 두 수의 합

https://www.acmicpc.net/problem/3273

3273번: 두 수의 합

package BAEKJOON.Silver.Ⅲ;

import java.util.Arrays;
import java.util.Scanner;

public class NO3273 {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int [] arr = new int [n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int x = sc.nextInt();
        Arrays.sort(arr);

        int start = 0;
        int end = n-1;
        int count = 0;

        while (start < end) {
            if( arr[start] + arr[end] == x ) {
                count ++;
                start ++;
                end --;
            } else {
                if ( arr[start] + arr[end] < x) {
                    start ++;
                } else {
                    end --;
                }
            }
        }
        System.out.println(count);

    }
}