2조 방민규 / 11월 1주차 / 목

daeun/boj1043.java

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+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.Scanner;
+
+public class Main {
+
+	static boolean visited[];
+
+	public static void main(String[] args) {
+		Scanner sc=  new Scanner(System.in);
+		int N= sc.nextInt(); //총 사람 수 (1부터)(노드 번호)
+		int M = sc.nextInt();//파티 수(간선 수)
+		int K = sc.nextInt();//진실아는 사람 수
+
+		visited = new boolean[N+1];
+		ArrayList<Integer>[] graph = new ArrayList[N+1];
+
+		for(int i=1; i<=N; i++) {
+			graph[i] = new ArrayList<>();
+		}
+
+		boolean[] knowT = new boolean[N+1];
+		for(int i=0; i<K; i++) {
+			int knowp = sc.nextInt();//아는 사람 번호
+			knowT[knowp] = true;
+		}
+
+
+		ArrayList<Integer>[] parties = new ArrayList[M];
+		for(int i=0; i<M; i++) {
+			int partynum = sc.nextInt();//각 파티마다 오는 사람 수
+			parties[i] = new ArrayList<>();
+			for(int j=0; j<partynum; j++) {
+				int p = sc.nextInt();
+				parties[i].add(p); //각 파티에 오는사람들 추가
+
+			}
+
+			for(int j =0; j<parties[i].size(); j++) {
+				for(int k=j+1; k<parties[i].size(); k++) {
+					graph[parties[i].get(j)].add(parties[i].get(k));
+					graph[parties[i].get(k)].add(parties[i].get(j));
+				}
+			}
+		}
+
+		for(int i=1; i<=N; i++) {
+			if(knowT[i] && !visited[i]) {
+				bfs(graph, i);
+
+			}
+		}
+
+		int cnt =0;
+		for(int i=0; i<M; i++) {
+			boolean dontknow = true;
+			for(int p :parties[i]) {
+				if(visited[p])
+					dontknow = false;
+					break;
+			}
+			if(dontknow) {
+
+				cnt++;
+			}
+		}
+
+		System.out.println(cnt);
+
+
+	}//main
+
+	static void bfs(ArrayList<Integer>[] graph, int num) {
+		Queue<Integer>q = new LinkedList<>();
+		q.add(num);
+		visited[num] = true;
+
+		while(!q.isEmpty()) {
+			int curr =q.poll();//현재 사람
+			for(int next: graph[curr]) { 
+				if(!visited[next]) {
+					visited[next] = true;
+					q.add(next);
+				}
+			}
+		}
+
+	}
+
+}

daeun/boj1068.java

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+
+public class boj1068 {
+
+}

daeun/boj1707.java

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+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.Scanner;
+
+public class 이분그래프 {
+
+	static int visited[];
+	static int V, E;
+	static boolean isgraph;
+
+
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+		int K = sc.nextInt();
+
+
+
+		for(int i=0; i<K; i++) {
+			isgraph = true;
+			 V = sc.nextInt();//정점 개수(1부터 시작)
+			 E = sc.nextInt();//간선ㄱ ㅐ수
+			 visited =  new int[V+1];
+			 ArrayList<Integer>[] graph = new ArrayList[V+1];
+			for(int j=1; j<=V; j++) {
+				graph[j] = new ArrayList<>();
+			}
+
+			for(int j=0; j<E; j++) {
+				int num1 = sc.nextInt();
+				int num2 = sc.nextInt();
+				graph[num1].add(num2);
+				graph[num2].add(num1);
+			}
+
+			for(int k=1; k<=V; k++) {
+				if(visited[k]==0) {
+					if(!bfs(graph, k)) {
+						isgraph= false;
+						break;
+					}
+				}
+
+			}
+
+			if(isgraph)
+				System.out.println("YES");
+			else 
+				System.out.println("NO");
+
+		}//k줄
+	}//main
+
+
+	static boolean bfs(ArrayList<Integer>[] graph, int num) {
+		Queue<Integer> q = new LinkedList<>();
+		q.add(num);
+		visited[num]=1;
+		while(!q.isEmpty()) {
+			int curr = q.poll();
+
+			for(int next: graph[curr]) {
+				if(visited[next]==0) {
+					visited[next] =(visited[curr]==1)? 2:1; 
+					q.add(next);
+				}else if(visited[next]==visited[curr]) {
+					return false;
+				}
+			}
+		}
+
+		return true;
+
+	}
+
+}

daeun/boj1967.java

@@ -0,0 +1,74 @@
+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 boj1967 {
+
+	static class Node {
+		int num;
+		int cost;
+
+		public Node(int num, int cost) {
+			this.num = num;//번호
+			this.cost = cost;//가중치
+		}
+
+
+	}
+
+	static boolean visited[];
+	static int sum;
+	static List<Node>[] tree;
+
+
+	public static void main(String[] args) throws NumberFormatException, IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		int N = Integer.parseInt(br.readLine());//노드 ㅅ서
+
+		tree = new ArrayList[N+1];
+
+		for(int i=1; i<=N; i++) {
+			tree[i] = new ArrayList<>();
+		}//트리 초기화
+
+
+		for(int i=1; i<N; i++) {
+			StringTokenizer st = new StringTokenizer(br.readLine());
+			int start = Integer.parseInt(st.nextToken());
+			int end = Integer.parseInt(st.nextToken());
+			int cost = Integer.parseInt(st.nextToken());
+
+
+			tree[start].add(new Node(end, cost));
+			tree[end].add(new Node(start, cost));//무망향인까
+		}
+		sum =0;
+
+		for(int i=1; i<=N; i++) {
+			visited = new boolean[N+1];
+			visited[i] = true;
+			dfs(i,0);
+		}
+
+		System.out.println(sum);
+
+	}//main
+
+
+	static void dfs(int num, int s) {
+
+		for(Node node: tree[num]) {
+			if(!visited[node.num]) {
+				visited[node.num] = true;
+				dfs(node.num, s+node.cost);
+			}
+		}
+
+		sum = sum<s? s: sum;
+	}
+
+
+}

daeun/boj2617.java

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+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.Scanner;
+
+public class Main {
+
+	static boolean visited[];
+
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+		int N = sc.nextInt(); // 구슬 갯수(1부터)
+		int M = sc.nextInt(); // 몇번 올렸는지(=간선
+		ArrayList<Integer>[] heavy = new ArrayList[N+1];
+		ArrayList<Integer>[] light = new ArrayList[N+1];
+
+		for(int i=1; i<=N; i++){
+		heavy[i] = new ArrayList<>();
+		light[i] = new ArrayList<>();
+		}
+
+		for (int i = 0; i < M; i++) {
+			int H = sc.nextInt(); // 무거운거
+			int L = sc.nextInt(); // 가벼운거
+			heavy[H].add(L);
+			light[L].add(H);
+		}
+		int margino = (N + 1) / 2;
+		int notmiddle=0;
+
+		for (int i = 1; i <= N; i++) {
+			visited = new boolean[N + 1];
+			int hcnt = bfs(heavy, i);
+			int lcnt = bfs(light, i);
+
+			if (hcnt >= margino || lcnt >= margino) {
+				notmiddle++;
+			}
+		}
+		System.out.println(notmiddle);
+
+	}// main
+
+	static int bfs(ArrayList<Integer>[] list, int num) {
+		Queue<Integer> q = new LinkedList<>();
+		q.add(num);
+		visited[num] = true;
+		int cnt = 0;
+		while (!q.isEmpty()) {
+			int curr = q.poll();
+			cnt++;
+			for (int next : list[curr]) {
+				if (!visited[next]) {
+					visited[next] = true;
+					q.add(next);
+				}
+			}
+		}
+		return cnt-1;
+	}
+}