중복 확인

내풀이>

import java.util.*;
public class Main {
    public String solution( int n, int[] arr) {
        String answer = "U";
        for (int i = 0; i < n-1; i++) {
            for (int j = i + 1; j < n; j++) {
                if (arr[i] == arr[j]) {
                    return "D";
                }
            }
        }
        return answer;
    }
    public static void main(String[] args) {
        Main T = new Main();
        Scanner kb = new Scanner(System.in);
        int n = kb.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = kb.nextInt();
        }
        System.out.println(T.solution(n,arr));
    }
}

내풀이2>
HashMap 사용

import java.util.*;
public class Main {
    public String solution( int n, int[] arr) {
        String answer = "U";
        HashMap<Integer, Integer> map = new HashMap<>();
        for (int x : arr) {
            if(map.containsKey(x)) return "D";
            else{
                map.put(x, map.getOrDefault(x,0)+1);
            }
        }
        return answer;
    }
    public static void main(String[] args) {
        Main T = new Main();
        Scanner kb = new Scanner(System.in);
        int n = kb.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = kb.nextInt();
        }
        System.out.println(T.solution(n,arr));
    }
}

다른풀이>

import java.util.*;
public class Main {
    public String solution( int n, int[] arr) {
        String answer = "U";
        Arrays.sort(arr);
        for (int i = 0; i < n - 1; i++) {
            if(arr[i] ==arr[i+1]) return "D";
        }
        return answer;
    }
    public static void main(String[] args) {
        Main T = new Main();
        Scanner kb = new Scanner(System.in);
        int n = kb.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = kb.nextInt();
        }
        System.out.println(T.solution(n,arr));
    }
}