From 68e9948471e7f037206aa934872edd9b1c0f5502 Mon Sep 17 00:00:00 2001
From: JHLEE325 <82587652+JHLEE325@users.noreply.github.com>
Date: Sun, 22 Feb 2026 00:04:12 +0900
Subject: [PATCH] =?UTF-8?q?[20260221]=20BOJ=20/=20G4=20/=20Puyo=20Puyo=20/?=
 =?UTF-8?q?=20=EC=9D=B4=EC=A4=80=ED=9D=AC?=
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---
 JHLEE325/202602/21 BOJ G4 Puyo Puyo.md | 90 ++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 JHLEE325/202602/21 BOJ G4 Puyo Puyo.md

diff --git a/JHLEE325/202602/21 BOJ G4 Puyo Puyo.md b/JHLEE325/202602/21 BOJ G4 Puyo Puyo.md
new file mode 100644
index 00000000..f28e4054
--- /dev/null
+++ b/JHLEE325/202602/21 BOJ G4 Puyo Puyo.md	
@@ -0,0 +1,90 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static char[][] map = new char[12][6];
+    static int[] dr = {-1, 1, 0, 0};
+    static int[] dc = {0, 0, -1, 1};
+    static boolean isPopped;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        for (int i = 0; i < 12; i++) {
+            map[i] = br.readLine().toCharArray();
+        }
+
+        int chainCount = 0;
+        while (true) {
+            isPopped = false;
+            boolean[][] visited = new boolean[12][6];
+
+            for (int i = 0; i < 12; i++) {
+                for (int j = 0; j < 6; j++) {
+                    if (map[i][j] != '.' && !visited[i][j]) {
+                        bfs(i, j, visited);
+                    }
+                }
+            }
+
+            if (!isPopped) break;
+
+            fall();
+            chainCount++;
+        }
+
+        System.out.println(chainCount);
+    }
+
+    static void bfs(int r, int c, boolean[][] visited) {
+        List<int[]> puyos = new ArrayList<>();
+        Queue<int[]> q = new LinkedList<>();
+        char color = map[r][c];
+
+        q.add(new int[]{r, c});
+        puyos.add(new int[]{r, c});
+        visited[r][c] = true;
+
+        while (!q.isEmpty()) {
+            int[] cur = q.poll();
+
+            for (int i = 0; i < 4; i++) {
+                int nr = cur[0] + dr[i];
+                int nc = cur[1] + dc[i];
+
+                if (nr >= 0 && nr < 12 && nc >= 0 && nc < 6) {
+                    if (!visited[nr][nc] && map[nr][nc] == color) {
+                        visited[nr][nc] = true;
+                        q.add(new int[]{nr, nc});
+                        puyos.add(new int[]{nr, nc});
+                    }
+                }
+            }
+        }
+
+        if (puyos.size() >= 4) {
+            for (int[] p : puyos) {
+                map[p[0]][p[1]] = '.';
+            }
+            isPopped = true;
+        }
+    }
+
+    static void fall() {
+        for (int c = 0; c < 6; c++) {
+            for (int r = 11; r > 0; r--) {
+                if (map[r][c] == '.') {
+                    for (int k = r - 1; k >= 0; k--) {
+                        if (map[k][c] != '.') {
+                            map[r][c] = map[k][c];
+                            map[k][c] = '.';
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+```