[20250826] BOJ / G1 / 동전 뒤집기 / 김민진

zinnnn37/202508/26 BOJ G1 동전 뒤집기.md

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+```java
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+
+public class BJ_1285_동전_뒤집기 {
+
+    private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+
+    private static int N;
+    private static int ans;
+    private static int[] coins;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        sol();
+    }
+
+    private static void init() throws IOException {
+        N = Integer.parseInt(br.readLine());
+        ans = Integer.MAX_VALUE;
+
+        coins = new int[N];
+        for (int i = 0; i < N; i++) {
+            String s = br.readLine();
+            for (int j = 0; j < N; j++) {
+                if (s.charAt(j) == 'T') {
+                    coins[i] += (1 << j);
+                }
+            }
+        }
+    }
+
+    private static void sol() throws IOException {
+        // 행 뒤집기
+        for (int rowFillped = 0; rowFillped < (1 << N); rowFillped++) {
+            // 뒷면
+            int totalTails = 0;
+
+            for (int row = 0; row < N; row++) {
+                // 0일 때 뒤집지 않고(0), 1일 때 뒤집을 때(1) 0이 되어야 해서 XOR 연산
+                int tailsInCol = Integer.bitCount(coins[row] ^ rowFillped);
+                totalTails += Math.min(tailsInCol, N - tailsInCol);
+            }
+            ans = Math.min(ans, totalTails);
+        }
+
+        bw.write(ans + "");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static int countTails(boolean[][] arr) {
+        int cnt = 0;
+        for (int i = 0; i < N; i++) {
+            for (int j = 0; j < N; j++) {
+                if (arr[i][j]) {
+                    cnt++;
+                }
+            }
+        }
+        return cnt;
+    }
+}
+```