[20250909] PGM / LV2 / [1차] 프렌즈4블록 / 김수연

suyeun84/202509/09 PGM LV2 [1차] 프렌즈4블록.md

@@ -0,0 +1,74 @@
+	```java
+import java.util.*;
+class Solution {
+    static int[][] dir = new int[][]{{0,0}, {0, 1}, {1,0}, {1,1}};
+    static int M, N, answer = 0;
+    static char[][] map;
+    public int solution(int m, int n, String[] board) {
+        M = m;
+        N = n;
+        map = new char[M][N];
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                map[i][j] = board[i].charAt(j);
+            }
+        }
+        boolean flag = true;
+        while (flag) {
+            flag = check();
+        }
+        return answer;
+    }
+    // 없앨 수 있는 block 찾기
+    private boolean check() {
+        boolean[][] remove = new boolean[M][N];
+        boolean flag = false;
+        for (int i = 0; i < M-1; i++) {
+            for (int j = 0; j < N-1; j++) {
+                char curr = map[i][j];
+                if (curr == '0') continue;
+                if (curr == map[i+1][j] && curr == map[i][j+1] && curr == map[i+1][j+1]) {
+                    for (int[] d : dir) {
+                        int ny = i + d[0];
+                        int nx = j + d[1];
+                        if (!remove[ny][nx]) answer++;
+                        remove[ny][nx] = true;
+                    }
+                    flag = true;
+                }
+            }
+        }
+        if (flag) move(remove);
+        return flag;
+    }
+
+    private void move(boolean[][] remove) {
+        for (int j = 0; j < N; j++) { // 각 열마다
+            Stack<Character> stack = new Stack<>();
+
+            for (int i = 0; i < M; i++) {
+                if (!remove[i][j] && map[i][j] != '0') {
+                    stack.push(map[i][j]);
+                }
+            }
+
+            for (int i = M - 1; i >= 0; i--) {
+                if (!stack.isEmpty()) {
+                    map[i][j] = stack.pop();
+                } else {
+                    map[i][j] = '0';
+                }
+            }
+        }
+    }
+
+
+    class Point {
+        int y, x;
+        public Point(int y, int x) {
+            this.y = y;
+            this.x = x;
+        }
+    }
+}
+```