13주차 문제풀이 (고동우)

baekjoon/11967_불켜기/src/dongwoo.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+import java.util.StringTokenizer;
+
+public class dongwoo {
+	static int[] dx = new int[] { 0, 1, 0, -1 };
+	static int[] dy = new int[] { 1, 0, -1, 0 };
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringTokenizer st = new StringTokenizer(br.readLine());
+		Map<Tuple, List<Tuple>> switches = new HashMap<>();
+		int N = Integer.parseInt(st.nextToken());
+		int M = Integer.parseInt(st.nextToken());
+		boolean[][] map = new boolean[N][N];
+		boolean[][] visited = new boolean[N][N];
+		for (int i = 0; i < M; i++) {
+			st = new StringTokenizer(br.readLine());
+			int[] from = new int[] { Integer.parseInt(st.nextToken()) - 1, Integer.parseInt(st.nextToken()) - 1 };
+			int[] to = new int[] { Integer.parseInt(st.nextToken()) - 1, Integer.parseInt(st.nextToken()) - 1 };
+			if (!switches.containsKey(new Tuple(from))) {
+				switches.put(new Tuple(from), new ArrayList<>());
+			}
+			switches.get(new Tuple(from)).add(new Tuple(to));
+		}
+		Queue<Tuple> q = new ArrayDeque<>();
+		q.add(new Tuple(new int[] { 0, 0 }));
+		visited[0][0] = true;
+		map[0][0] = true;
+		int cnt = 1;
+
+		while (!q.isEmpty()) {
+			Tuple now = q.poll();
+
+			// 현재 위치에서 켤 수 있는 불 다 켜기, 새로 불켠곳이 visited와 인접해있으면 queue에 추가 
+			for (Tuple pos : switches.getOrDefault(now, new ArrayList<>())) {
+				int x = pos.tuple[0];
+				int y = pos.tuple[1];
+				if (!map[x][y]) {
+					cnt++;
+				}
+				map[x][y] = true;
+				for (int i = 0; i < 4; i++) {
+					int newX = x + dx[i];
+					int newY = y + dy[i];
+					boolean val;
+					try {
+						val = map[newX][newY];
+					} catch (Exception e) {
+						continue;
+					}
+					if (visited[newX][newY] && !visited[x][y]) {
+						q.add(new Tuple(new int[] { x, y }));
+						visited[x][y] = true;
+						break;
+					}
+				}
+			}
+			// bfs로 주변 탐색하기. 
+			for (int i = 0; i < 4; i++) {
+				int x = now.tuple[0];
+				int y = now.tuple[1];
+				int newX = x + dx[i];
+				int newY = y + dy[i];
+				boolean val;
+				try {
+					val = map[newX][newY];
+				} catch (Exception e) {
+					continue;
+				}
+				if (visited[newX][newY] || !val) {
+					continue;
+				}
+				q.add(new Tuple(new int[] { newX, newY }));
+				visited[newX][newY] = true;
+
+			}
+		}
+		System.out.println(cnt);
+	}
+}
+
+class Tuple {
+	int[] tuple;
+
+	public Tuple(int[] list) {
+		tuple = list;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		return Arrays.equals(tuple, ((Tuple) obj).tuple);
+	}
+
+	@Override
+	public int hashCode() {
+		return 100*tuple[0]+tuple[1];
+	}
+
+}

baekjoon/14908_구두수선공/src/dongwoo.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class dongwoo {
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		int N = Integer.parseInt(br.readLine());
+		StringBuilder sb = new StringBuilder();
+		Work[] works = new Work[N];
+		for (int i = 0; i < N; i++) {
+			StringTokenizer st = new StringTokenizer(br.readLine());
+			works[i] = new Work(i + 1, Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()));
+		}
+
+		Arrays.sort(works);
+
+		for (int i = 0; i < N; i++) {
+			sb.append(works[i].number).append(" ");
+		}
+		System.out.println(sb);
+	}
+
+}
+
+class Work implements Comparable<Work> {
+	int number;
+	int time;
+	int S;
+
+	public Work(int number, int time, int S) {
+		this.number = number;
+		this.time = time;
+		this.S = S;
+	}
+
+	@Override
+	public int compareTo(Work w) {
+//		double here = Math.round((double) S * 100000 / time);
+//		double other = Math.round((double) w.S * 100000 / w.time);
+		double here = (double) S * 100000 / time;
+		double other = (double) w.S * 100000 / w.time;
+		// 작업 효율 비교 (보상금 대비 걸리는 시간  )
+		if (here != other) {
+			if (here - other > 0) {
+				return -1;
+			}
+			if (here - other < 0) {
+				return 1;
+			}
+			// 효율이 같으면 시간이 적게 걸리는 순서 
+			return this.time - w.time;
+		}
+		// 시간도 같다면 오름차순 
+		return this.number - w.number;
+	}
+
+}

baekjoon/14927_전구끄기/src/dongwoo.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.StringTokenizer;
+
+public class dongwoo {
+	static boolean[][] map;
+	static int[] di = new int[] { 0, 0, 1, 0, -1 };
+	static int[] dj = new int[] { 0, 1, 0, -1, 0 };
+	static int min = Integer.MAX_VALUE;
+	static int N;
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		N = Integer.parseInt(br.readLine());
+		map = new boolean[N+1][N];
+		for (int i = 0; i < N; i++) {
+			StringTokenizer st = new StringTokenizer(br.readLine());
+			for (int j = 0; j < N; j++) {
+				if (Integer.parseInt(st.nextToken()) == 1) {
+					map[i + 1][j] = true;
+				}
+			}
+		}
+		for (int i = 0; i < 1<<N; i++) {
+			for (int j = 0; j < N; j++) {
+				if ((i & (1 << j)) == (1 << j)) {
+					map[0][j] = true;
+				} else {
+					map[0][j] = false;
+				}
+			}
+			checkLine(0, 0);
+		}
+
+		if (min == Integer.MAX_VALUE) {
+			System.out.println(-1);
+		} else {
+			System.out.println(min);
+		}
+	}
+
+	private static void checkLine(int i, int clickCnt) {
+		List<Integer> searchable = new ArrayList<>();
+		for (int j = 0; j < N; j++) {
+			if (map[i][j]) {
+				searchable.add(j);
+			}
+		}
+		if (i == N) {
+			if (searchable.isEmpty()) {
+				min = Math.min(min, clickCnt);
+			}
+			return;
+		}
+		for (int j = 0; j < searchable.size(); j++) {
+			int pos = searchable.get(j);
+			clickSwitch(i + 1, pos);
+		}
+		checkLine(i + 1, searchable.size() + clickCnt);
+		for (int j = 0; j < searchable.size(); j++) {
+			int pos = searchable.get(j);
+			clickSwitch(i + 1, pos);
+		}
+
+	}
+
+	private static void clickSwitch(int i, int j) {
+		for (int k = 0; k < 5; k++) {
+			int newI = i + di[k];
+			int newJ = j + dj[k];
+			boolean val;
+			try {
+				val = map[newI][newJ];
+			} catch (Exception e) {
+				continue;
+			}
+			map[newI][newJ] = !val;
+		}
+	}
+}

baekjoon/2904_수학은너무쉬워/src/dongwoo.java

@@ -0,0 +1,83 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.StringTokenizer;
+
+public class dongwoo {
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringBuilder sb = new StringBuilder();
+		int N = Integer.parseInt(br.readLine());
+		int[] numbers = new int[N];
+		StringTokenizer st = new StringTokenizer(br.readLine());
+		Map<Integer, Integer> soinsubunhae = new HashMap<>();	// 등장하는 모든 숫자를 곱해서 소인수분해 때려놓은거 
+		for (int i = 0; i < N; i++) {
+			numbers[i] = Integer.parseInt(st.nextToken());
+			disAssemble(numbers[i], soinsubunhae);
+		}
+
+		int maximumValue = 1;
+		Map<Integer, Integer> soinsubunhaeNanungeo = new HashMap<>();	// 소인수분해 한 결과를 N으로 나눈거 
+		for (Integer i : soinsubunhae.keySet()) {
+			int cnt = soinsubunhae.get(i);
+			if (cnt / N > 0) {
+				maximumValue *= (int) Math.pow(i, (cnt / N));
+				soinsubunhaeNanungeo.put(i, soinsubunhaeNanungeo.getOrDefault(i, 0) + cnt / N);
+			}
+		}
+		sb.append(maximumValue).append(" ");
+
+		// 각 숫자마다 돌면서 부족한 숫자 채워넣기 
+		int moves = 0;
+		for (int i = 0; i < N; i++) {
+			Map<Integer, Integer> res = new HashMap<>();
+			disAssemble(numbers[i], res);
+			for (Integer n : soinsubunhaeNanungeo.keySet()) {
+				if (soinsubunhaeNanungeo.get(n) > res.getOrDefault(n, 0)) {
+					moves += soinsubunhaeNanungeo.get(n) - res.getOrDefault(n, 0);
+				}
+			}
+		}
+		sb.append(moves);
+		System.out.println(sb);
+
+	}
+
+	// 소인수분해
+	public static void disAssemble(int N, Map<Integer, Integer> result) {
+		if (N == 1) {
+			return;
+		}
+		if (isPrime(N)) {
+			if (result.containsKey(N)) {
+				result.put(N, result.get(N) + 1);
+			} else {
+				result.put(N, 1);
+			}
+			return;
+		}
+		for (int i = (int) Math.sqrt(N) + 1; i > 1; i--) {
+			if (N % i == 0) {
+				disAssemble(N / i, result);
+				disAssemble(i, result);
+				break;
+			}
+		}
+
+	}
+
+	private static boolean isPrime(int N) {
+		if (N < 2) {
+			return false;
+		}
+		for (int i = 2; i <= Math.sqrt(N); i++) {
+			if (N % i == 0) {
+				return false;
+			}
+		}
+		return true;
+	}
+
+}