[BOJ/JAVA] 백준 1717번 : 집합의 표현

1717번: 집합의 표현

 

 

 

 

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• 풀이

 

 

0일경우 합집합 연산, 1일 경우 교집합 확인이다.

 

합집합의 경우 합집합 연산의 대표적인 유니온파인드 알고리즘을 사용했다.

 

 

 

• 코드

 

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

public class Main {
	static int N, M;
	static int[] parent;
	static StringBuilder sb;

	public static void main(String[] args) throws Exception {
		SetData();
		System.out.println(sb);
	}

	// 데이터
	private static void SetData() throws Exception {
		InputReader in = new InputReader(System.in);

		N = in.nextInt();
		M = in.nextInt();
		sb = new StringBuilder();
		parent = new int[N+1];
		
		for (int i = 1; i <= N; i++) {
			parent[i] = i;
		}
		
		for(int i = 0 ; i < M; i++) {
			if(in.nextInt() == 0) {
				Union(in.nextInt(), in.nextInt());
			} else {
				CheckUnion(in.nextInt(), in.nextInt());
			}
		}
	}
	
    public static int find(int x) {
        if (x == parent[x])   
        	return x;
        else    	
		return parent[x] = find(parent[x]);
    }
 
    public static void Union(int x, int y) {
        x = find(x);
        y = find(y);
 
        if (x == y)  return;
        
        if (x < y) 
            parent[y] = x;
        else 
            parent[x] = y;
        
    }
	
    public static void CheckUnion(int x, int y) { 
        if (find(x) == find(y)) 
            sb.append("YES").append("\n");
        else
            sb.append("NO").append("\n");
    }
}

class InputReader {
	private final InputStream stream;
	private final byte[] buf = new byte[8192];
	private int curChar, snumChars;

	public InputReader(InputStream st) {
		this.stream = st;
	}

	public int read() {
		if (snumChars == -1)
			throw new InputMismatchException();
		if (curChar >= snumChars) {
			curChar = 0;
			try {
				snumChars = stream.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (snumChars <= 0)
				return -1;
		}
		return buf[curChar++];
	}

	public int nextInt() {
		int c = read();
		while (isSpaceChar(c)) {
			c = read();
		}
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		int res = 0;
		do {
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public long nextLong() {
		int c = read();
		while (isSpaceChar(c)) {
			c = read();
		}
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		long res = 0;
		do {
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public int[] nextIntArray(int n) {
		int a[] = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = nextInt();
		}
		return a;
	}

	public String nextLine() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuilder res = new StringBuilder();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isEndOfLine(c));
		return res.toString();
	}

	public boolean isSpaceChar(int c) {
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	private boolean isEndOfLine(int c) {
		return c == '\n' || c == '\r' || c == -1;
	}
}