Merge pull request #1939 from AlgorithmWithGod/Ukj0ng

[20260216] BOJ / G3 / 피리 부는 사나이 / 한종욱

Author: ShinHeeEul

Ukj0ng/202602/16 BOJ G3 피리 부는 사나이.md

@@ -0,0 +1,89 @@
+```
+import java.io.*;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.StringTokenizer;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static Set<Integer> set;
+    private static char[][] map;
+    private static int[] uf, size;
+    private static int N, M;
+
+    public static void main(String[] args) throws IOException {
+        init();
+
+        for (int i = 0; i < N; i++) {
+            for (int j = 0; j < M; j++) {
+                int x = i*M + j;
+                int y = 0;
+                int nx = i;
+                int ny = j;
+                if (map[i][j] == 'U') nx--;
+                else if (map[i][j] == 'D') nx++;
+                else if (map[i][j] == 'L') ny--;
+                else ny++;
+
+                y = nx*M + ny;
+                int root1 = find(x);
+                int root2 = find(y);
+
+                if (root1 == root2) continue;
+                union(root1, root2);
+            }
+        }
+
+        for (int i = 0; i < N*M; i++) {
+            set.add(find(i));
+        }
+
+        bw.write(set.size() + "\n");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        map = new char[N][M];
+
+        for (int i = 0; i < N; i++) {
+            String input = br.readLine();
+            for (int j = 0; j < M; j++) {
+                map[i][j] = input.charAt(j);
+            }
+        }
+
+        uf = new int[N*M];
+        size = new int[N*M];
+
+        for (int i = 0; i < N*M; i++) {
+            uf[i] = i;
+            size[i] = 1;
+        }
+
+        set = new HashSet<>();
+    }
+
+    private static void union(int x, int y) {
+        if (size[x] < size[y]) {
+            uf[x] = y;
+            size[y] += size[x];
+        } else {
+            uf[y] = x;
+            size[x] += size[y];
+        }
+    }
+
+    private static int find(int x) {
+        if (uf[x] == x) return x;
+
+        return uf[x] = find(uf[x]);
+    }
+}
+```