Merge pull request #1979 from AlgorithmWithGod/JHLEE325

[20260228] BOJ / G4 / 체스판 다시 칠하기 2 / 이준희

Author: ShinHeeEul

JHLEE325/202602/28 BOJ G4 체스판 다시 칠하기 2.md

@@ -0,0 +1,54 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    static int N, M, K;
+    static char[][] board;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+        K = Integer.parseInt(st.nextToken());
+
+        board = new char[N + 1][M + 1];
+        for (int i = 1; i <= N; i++) {
+            String line = br.readLine();
+            for (int j = 1; j <= M; j++) {
+                board[i][j] = line.charAt(j - 1);
+            }
+        }
+
+        System.out.println(Math.min(coloring('B'), coloring('W')));
+    }
+
+    static int coloring(char start) {
+        int[][] sum = new int[N + 1][M + 1];
+
+        for (int i = 1; i <= N; i++) {
+            for (int j = 1; j <= M; j++) {
+                int value = 0;
+                if ((i + j) % 2 == 0) {
+                    if (board[i][j] != start) value = 1;
+                } else {
+                    if (board[i][j] == start) value = 1;
+                }
+
+                sum[i][j] = sum[i - 1][j] + sum[i][j - 1] - sum[i - 1][j - 1] + value;
+            }
+        }
+
+        int painting = Integer.MAX_VALUE;
+        for (int i = K; i <= N; i++) {
+            for (int j = K; j <= M; j++) {
+                int count = sum[i][j] - sum[i - K][j] - sum[i][j - K] + sum[i - K][j - K];
+                painting = Math.min(painting, count);
+            }
+        }
+        return painting;
+    }
+}
+```