[BOJ] 백준 1253 좋다

[문제]

https://www.acmicpc.net/problem/1253

 

 

[소스 코드]

import java.io.*;
import java.util.*;
public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st;
		int n = Integer.parseInt(br.readLine());
		int[] arr = new int[n];
		st = new StringTokenizer(br.readLine());
		for(int i=0;i<n;i++) {
			arr[i] = Integer.parseInt(st.nextToken());
		}
		Arrays.sort(arr);
		int result = 0;
		for(int i=0;i<n;i++) {
			int start = 0;
			int end = n - 1;
			while(start<end) {
				int sum = arr[start] + arr[end];
				if(sum==arr[i]) {
					if(start==i || end==i) {
						if(start==i) {
							start++;
						}
						else
							end--;
					}
					else {
						result++;
						break;
					}
				}
				else {
					if(sum<arr[i])
						start++;
					else
						end--;
				}
			}
		}
		System.out.println(result);
	}
}