Kjh 3주차

source/KJH/그래프탐색/220524/bj3184.md

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+## 양
+
+dfs/bfs 다시 시작하겠습니다..
+
+```java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.util.StringTokenizer;
+
+public class Main{
+    static int R,C;
+    static char[][] maps;
+    static boolean[][] visited;
+    static int dx[] = {1,0,-1,0};
+    static int dy[] = {0,1,0,-1};
+    static Queue<int[]> queue = new LinkedList<>();
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        R = Integer.parseInt(st.nextToken());
+        C = Integer.parseInt(st.nextToken());
+        visited =new boolean[R][C];
+        maps = new char[R][C];
+
+        int vcount = 0;
+        int ocount =0;
+        for(int i=0; i<R; i++){
+            String s = br.readLine();
+            for(int j=0; j<C; j++){
+                char x = s.charAt(j);
+                maps[i][j] = x;
+
+
+            }
+        }
+
+
+        for(int i=0; i<R; i++){
+            for(int j=0; j<C; j++){
+                if(!visited[i][j] && maps[i][j] == 'V'){
+                    dfs(i,j);
+                }
+            }
+        }
+}
+
+    public static void dfs(int x ,int y){
+        visited[x][y] = true;
+        int ocount =0;
+        int vcount =0;
+        queue.add(new int[]{x,y});
+        while(!queue.isEmpty()){
+            int[] now = queue.poll();
+            int nowX = now[0];
+            int nowY = now[1];
+
+            for(int i=0; i<4; i++){
+                int nX = nowX + dx[i];
+                int nY = nowY + dy[i];
+
+                if(nX >=0 && nX < R && nY >=0 && nY < C){
+                    if(maps[nX][nY] == 'V' && !visited[nX][nY]){
+                        queue.add(new int[]{nX,nY});
+                        vistied[nX][nY] = true;
+                        vcount +=1;
+                    }
+                    else if(maps[nX][nY] == '#'){
+                        continue;
+                    }
+                    else if(maps[nX][nY] == '.' && !visited[nX][nY]){
+                        queue.add(new int[]{nX,nY});
+                        visited[nX][nY] = true;
+                    }
+                    else if(maps[nX][nY] == 'O'){
+                        ocount += 1;
+                    }
+                }
+
+            }
+        }
+    }
+}
+```

source/KJH/그래프탐색/220525/bj2606.md

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+## 바이러스
+
+예전에 풀었던 문제라 쉬웠따
+bfs지만, queue를 사용하지 않고 재귀를 통해 풀었다. 
+
+```java
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.util.StringTokenizer;
+import java.util.*;
+import java.io.*;
+
+public class Main{
+
+    static int n,m;
+    static  ArrayList<Integer>[] arrayList;
+    static boolean[] visited;
+    static int count=0;
+    public static void main(String[] args)throws IOException{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        n = Integer.parseInt(br.readLine()); //컴퓨터 수
+        m = Integer.parseInt(br.readLine()); //컴퓨터 번호 쌍
+        arrayList = new ArrayList[n+1];
+        visited = new boolean[n+1];
+
+        for(int i=1; i<=n; i++){
+            arrayList[i] = new ArrayList<Integer>();
+        }
+
+        for(int i=0; i<m; i++){
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int x = Integer.parseInt(st.nextToken());
+            int y = Integer.parseInt(st.nextToken());
+            arrayList[x].add(y);
+            arrayList[y].add(x);
+        }
+
+        bfs(1);
+        System.out.println(count);
+    }
+
+    public static void bfs(int num){
+        visited[num] = true;
+
+        for(int x : arrayList[num]){
+            if(!visited[x]){
+                count+=1;
+                bfs(x);
+            }
+        }
+
+
+    }
+}
+```