Java Set

개요

각 값이 겹치지 않고 고유한 값을 가진 collection 이다

합집합, 차집합, 교집합 연산이 가능하다

• hash set 예제

Java

CPU

1.3s

MEM

77M

0.8s

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import java.util.HashSet;

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

    HashSet<Integer> numbers = new HashSet<Integer>();

    numbers.add(4);
    numbers.add(7);
    numbers.add(8);

    for(int i = 1; i <= 10; i++) {
      if(numbers.contains(i)) {
        System.out.println(i + " was found in the set.");
      } else {
        System.out.println(i + " was not found in the set.");
      }
    }
  }
}

1 was not found in the set.
2 was not found in the set.
3 was not found in the set.
4 was found in the set.
5 was not found in the set.
6 was not found in the set.
7 was found in the set.
8 was found in the set.
9 was not found in the set.
10 was not found in the set.

• 집합 연산 예제

Java

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//Please don't change class name 'Main'
import java.util.ArrayList;
import java.util.HashSet;

import java.util.Iterator;

class Main {

    public static void main(String[] args) {
        HashSet<Integer> A = new HashSet<Integer>();
        A.add(1);
        A.add(2);
        A.add(3);

        HashSet<Integer> B = new HashSet<Integer>();
        B.add(3);
        B.add(4);
        B.add(5);

        HashSet<Integer> C = new HashSet<Integer>();
        C.add(1);
        C.add(2);


        A.addAll(B);
		System.out.print("합집합 결과 ");
		for(int n : A) System.out.print(n + " ");
		System.out.println();
        B.retainAll(C);
		System.out.print("교집합 결과 ");
		for(int n : B) System.out.print(n + " ");
		System.out.println();
        A.removeAll(B);
		System.out.print("차집합 결과 ");
		for(int n : A) System.out.print(n + " ");
		System.out.println();
    }
}

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