Merge pull request #132 from yejincode/week12

feat: 12주차 - 예진

yejin/song/BOJ_좌표정렬하기.java

@@ -0,0 +1,35 @@
+package yejin.song;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class BOJ_좌표정렬하기 {
+    public static void main(String[] args) throws Exception{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        int N = Integer.parseInt(br.readLine());
+
+        int arr[][] = new int[N][2];
+
+        for (int i =0; i<N; i++){
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            arr[i][0] = Integer.parseInt(st.nextToken());
+            arr[i][1] = Integer.parseInt(st.nextToken());
+        }
+
+        Arrays.sort(arr, (e1,e2) -> {
+            if(e1[0] == e2[0]){
+                return e1[1] - e2[1];
+            }
+            else return e1[0] - e2[0];
+        });
+
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i< N; i++){
+            sb.append(arr[i][0]+ " " + arr[i][1]).append('\n');
+        }
+        System.out.println(sb);
+    }
+}

yejin/song/BOJ_토마토.java

@@ -0,0 +1,104 @@
+package yejin.song;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.StringTokenizer;
+
+public class BOJ_토마토 {
+    static boolean visited[][];
+    static int map[][];
+    static int[] dx = {-1,1,0,0};
+    static int[] dy = {0,0,-1,1};
+    static int N;
+    static int M;
+    static Queue<Tomato> queue;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine(), " ");
+
+        M = Integer.parseInt(st.nextToken()); //6
+        N = Integer.parseInt(st.nextToken()); //4
+
+        int days = 0;
+
+        visited = new boolean[N][M];
+        map = new int[N][M]; //int[4][6]
+
+        int zeroCount = 0;
+        queue = new LinkedList<>();
+
+        // 맵 초기화
+        // 1인 경우(익은 토마토) 시작점이므로 큐에 넣기
+        for (int i = 0; i<N ; i++){
+            st = new StringTokenizer(br.readLine()," ");
+            for (int j = 0; j< M; j++){
+                int value = Integer.parseInt(st.nextToken());
+                map[i][j] = value;
+                if (value == 0) zeroCount++;
+                else if (value == 1) {
+                    visited[i][j] = true;
+                    queue.add(new Tomato(i,j,0)); // 좌표값을 담는다.
+                }
+                // 1,5 (N,M)
+            }
+        }
+
+        // 최초 초기화된 맵에 0이 없는 경우 : 0 출력
+        if(zeroCount == 0) {
+            System.out.println(0);
+            return;
+        }else if(queue.isEmpty()){ // 익은 토마토(1)가 입력되지 않은 경우
+            System.out.println(-1);
+            return;
+        }
+
+        // 큐에 담길 때마다 기존 큐 day++;
+        while (!queue.isEmpty()){
+            Tomato tomato = queue.poll();
+            bfs(tomato);
+            if (queue.isEmpty()) days = tomato.day;
+        }
+
+        for (int i = 0; i<N; i++){
+            for (int j =0; j<M; j++){
+                if(map[i][j] == 0) {
+                    System.out.println(-1);
+                    return;
+                }
+            }
+        }
+        System.out.println(days);
+    }
+
+    static void bfs(Tomato tomato){
+        int x = tomato.x;
+        int y = tomato.y;
+        int day = tomato.day;
+
+        for (int i = 0; i < 4; i++){
+            int nx = x + dx[i];
+            int ny = y + dy[i];
+
+            // 탐색 좌표가 조건에 만족한다면 (탐색좌표가 0<= 좌표 <N/M , visited가 false, 좌표에 해당하는 값이 0 )
+            if (nx >= 0 && nx < N && ny >= 0 && ny < M && !visited[nx][ny] && map[nx][ny] == 0){
+                map[nx][ny] = 1;
+                visited[nx][ny] = true;
+                queue.add(new Tomato(nx, ny, day+1));
+            }
+        }
+    }
+
+    static class Tomato{
+        int x, y, day;
+
+        public Tomato(int x,int y,int day){
+            this.x = x;
+            this.y = y;
+            this.day = day;
+        }
+    }
+}