[20251215] BOJ / G2 / 벽 부수고 이동하기 4 / 김민진

Author: zinnnn37

zinnnn37/202512/15 BOJ G2 벽 부수고 이동하기 4.md

@@ -2,7 +2,6 @@
 import java.awt.*;
 import java.io.*;
 import java.util.*;
-import java.util.List;
 import java.util.Queue;
 
 public class BJ_16946_벽_부수고_이동하기_4 {
@@ -19,7 +18,7 @@ public class BJ_16946_벽_부수고_이동하기_4 {
     private static int[][]               matrix;
     private static boolean[][]           visited;
     private static Queue<Point>          q;
-    private static List<Integer>         list;
+    private static Set<Integer>          set;
     private static Map<Integer, Integer> groups;
 
     public static void main(String[] args) throws IOException {
@@ -42,7 +41,7 @@ public class BJ_16946_벽_부수고_이동하기_4 {
         }
         visited = new boolean[N][M];
         q = new ArrayDeque<>();
-        list = new ArrayList<>();
+        set = new HashSet<>();
         groups = new HashMap<>();
     }
 
@@ -97,14 +96,14 @@ public class BJ_16946_벽_부수고_이동하기_4 {
                     sb.append(0);
                 } else {
                     cnt = 1;
-                    list.clear();
+                    set.clear();
                     for (int d = 0; d < 4; d++) {
                         int nx = i + dx[d];
                         int ny = j + dy[d];
 
-                        if (OOB(nx, ny) || matrix[nx][ny] == 1 || list.contains(matrix[nx][ny])) continue;
+                        if (OOB(nx, ny) || matrix[nx][ny] == 1 || set.contains(matrix[nx][ny])) continue;
 
-                        list.add(matrix[nx][ny]);
+                        set.add(matrix[nx][ny]);
                         cnt += groups.get(matrix[nx][ny]);
                     }
                     sb.append(cnt % 10);