[백준 1940] 주몽의 명령(투 포인터)

문제

https://www.acmicpc.net/problem/1940

1940번: 주몽

 

코드

package org.kyhslam.DoItAlgorithm.ch02;

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

public class p1940 {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int M = sc.nextInt();

        int[] arr = new int[N];

        //6
        //7
        //  2 7 4 1 5 3
        for (int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        }

        arrView(arr);
        System.out.println("sort --- ");
        Arrays.sort(arr);
        arrView(arr);

        int startIndex = 0;
        int endIndex = N-1;
        int answer = 0;

        while (startIndex < endIndex) {
            if (arr[startIndex] + arr[endIndex] > M) {
                endIndex--;
            } else if (arr[startIndex] + arr[endIndex] < M) {
                startIndex++;
            } else {
                startIndex++;
                endIndex--;
                answer++;
            }
        }

        System.out.println("answer = " + answer);


    }

    public static void arrView(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
    }
}