Merge pull request #433 from AlgorithmWithGod/Seol-JY

[20250710] BOJ / P4 / 불 끄기 / 설진영

Author: ShinHeeEul

Seol-JY/202507/10 BOJ P4 불 끄기.md

@@ -0,0 +1,64 @@
+```java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class Main {
+    static int[] map = new int[10];
+    static int sum;
+    static int minToggle = Integer.MAX_VALUE;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        for (int i = 0; i < 10; i++) {
+            String input = br.readLine();
+            for (int j = 0; j < 10; j++) {
+                if (input.charAt(j) == 'O') {
+                    map[i] |= (1 << j);
+                }
+            }
+        }
+
+        for (int firstRow = 0; firstRow < (1 << 10); firstRow++) {
+            int[] tempMap = map.clone();
+            int toggleCount = 0;
+            
+            for (int j = 0; j < 10; j++) {
+                if (isLightOn(firstRow, j)) {
+                    toggle(tempMap, 0, j);
+                    toggleCount++;
+                }
+            }
+            
+            for (int i = 1; i < 10; i++) {
+                for (int j = 0; j < 10; j++) {
+                    if (isLightOn(tempMap[i - 1], j)) {
+                        toggle(tempMap, i, j);
+                        toggleCount++;
+                    }
+                }
+            }
+            
+            if (tempMap[9] == 0) {
+                minToggle = Math.min(minToggle, toggleCount);
+            }
+        }
+        
+        System.out.println(minToggle == Integer.MAX_VALUE ? -1 : minToggle);
+    }
+
+    static boolean isLightOn(int row, int col) {
+        return (row & (1 << col)) != 0;
+    }
+
+    static void toggle(int[] map, int x, int y) {
+        map[x] ^= (1 << y);
+        
+        if (x > 0) map[x - 1] ^= (1 << y);
+        if (x < 9) map[x + 1] ^= (1 << y);
+        if (y > 0) map[x] ^= (1 << (y - 1));
+        if (y < 9) map[x] ^= (1 << (y + 1));
+    }
+}
+```