[20250824] PGM / LV2 / 석유 시추 / 이인희

LiiNi-coder/202508/25 PGM 석유 시추.md

@@ -0,0 +1,74 @@
+```java
+import java.util.*;
+
+class Solution {
+    private static int R
+    private static int C;
+    private static int[][] land;
+    private static int[][] idAtPoint;
+    private static boolean[][] visited;
+    private static int[] dr = {1, -1, 0, 0};
+    private static int[] dc = {0, 0, 1, -1};
+    private static List<Integer> countAtId;
+
+    public int solution(int[][] lland) {
+        land = lland;
+        R = land.length;
+        C = land[0].length;
+        visited = new boolean[R][C];
+        idAtPoint = new int[R][C];
+        countAtId = new ArrayList<>();
+        countAtId.add(0);//0생략
+        int id = 1;
+        for(int r=0; r<R; r++){
+            for(int c=0; c<C; c++){
+                if(land[r][c] == 1 && !visited[r][c]){
+                    bfs(r, c, id++);
+                }
+            }
+        }
+
+        int answer = 0;
+        for(int c=0; c<C; c++){
+            int oilAtCol = 0;
+            var passedId = new HashSet<Integer>();
+            for(int r=0; r<R; r++){
+                if(land[r][c] == 0) continue;
+                int IdAtP = idAtPoint[r][c];
+                if(passedId.contains(IdAtP)) continue;
+                passedId.add(IdAtP);
+                oilAtCol += countAtId.get(IdAtP);
+            }
+            answer = Math.max(answer, oilAtCol);
+        }
+        return answer;
+    }
+
+    private void bfs(int sr, int sc, int id){
+        var q = new ArrayDeque<int[]>();
+        q.add(new int[]{sr, sc});
+        visited[sr][sc] = true;
+        idAtPoint[sr][sc] = id;
+
+        int temp = 0;
+        while(!q.isEmpty()){
+            int[] cur = q.poll();
+            int r = cur[0]
+            int c = cur[1];
+            temp++;
+            for(int d=0; d<4; d++){
+                int nr = r + dr[d];
+                int nc = c + dc[d];
+                if(nr<0 || nr>=R || nc<0 || nc>=C) continue;
+                if(visited[nr][nc]) continue;
+                if(land[nr][nc] == 0) continue;
+                visited[nr][nc] = true;
+                idAtPoint[nr][nc] = id;
+                q.add(new int[]{nr, nc});
+            }
+        }
+        countAtId.add(temp);
+    }
+}
+
+```