[20251124] BOJ / P3 / 달리기

Author: Ukj0ng

Ukj0ng/202511/24 BOJ P3 달리기.md

@@ -0,0 +1,95 @@
+```
+import java.io.*;
+import java.util.ArrayDeque;
+import java.util.Queue;
+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 final int[] dx = {1, 0, -1, 0};
+    private static final int[] dy = {0, 1, 0, -1};
+    private static char[][] map;
+    private static int[][] dist, count;
+    private static int[] start, end;
+    private static int N, M, K;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        int answer = BFS();
+
+        bw.write(answer + "\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());
+        K = Integer.parseInt(st.nextToken());
+
+        map = new char[N + 1][M + 1];
+        dist = new int[N + 1][M + 1];
+        count = new int[N + 1][M + 1];
+
+        start = new int[2];
+        end = new int[2];
+
+        for (int i = 1; i <= N; i++) {
+            char[] input = br.readLine().toCharArray();
+            for (int j = 1; j <= M; j++) {
+                map[i][j] = input[j - 1];
+                dist[i][j] = Integer.MAX_VALUE;
+            }
+        }
+
+        st = new StringTokenizer(br.readLine());
+        start[0] = Integer.parseInt(st.nextToken());
+        start[1] = Integer.parseInt(st.nextToken());
+        end[0] = Integer.parseInt(st.nextToken());
+        end[1] = Integer.parseInt(st.nextToken());
+    }
+
+    private static int BFS() {
+        Queue<int[]> q = new ArrayDeque<>();
+        dist[start[0]][start[1]] = 0;
+        q.add(new int[]{start[0], start[1], 0});
+
+        while (!q.isEmpty()) {
+            int[] current = q.poll();
+
+            for (int i = 0; i < 4; i++) {
+                int nx = current[0];
+                int ny = current[1];
+                if (i % 2 == 0) {
+                    int k = 1;
+                    while (k <= K && !OOB(nx + dx[i] * k, ny) && map[nx + dx[i] * k][ny] == '.') {
+                        if (dist[nx + dx[i] * k][ny] < current[2] + 1) break;
+                        dist[nx + dx[i] * k][ny] = Math.min(dist[nx + dx[i] * k][ny], current[2] + 1);
+                        count[nx + dx[i] * k][ny]++;
+                        if (count[nx + dx[i] * k][ny] <= 2) q.add(new int[]{nx + dx[i] * k, ny, current[2] + 1});
+                        k++;
+                    }
+                } else {
+                    int k = 1;
+                    while (k <= K && !OOB(nx, ny + dy[i] * k) && map[nx][ny + dy[i] * k] == '.') {
+                        if (dist[nx][ny + dy[i] * k] < current[2] + 1) break;
+                        dist[nx][ny + dy[i] * k] = Math.min(dist[nx][ny + dy[i] * k], current[2] + 1);
+                        count[nx][ny + dy[i] * k]++;
+                        if (count[nx][ny + dy[i] * k] <= 2) q.add(new int[]{nx, ny + dy[i] * k, current[2] + 1});
+                        k++;
+                    }
+                }
+            }
+        }
+
+        return dist[end[0]][end[1]] != Integer.MAX_VALUE ? dist[end[0]][end[1]] : -1;
+    }
+
+    private static boolean OOB(int nx, int ny) {
+        return nx < 1 || nx > N || ny < 1 || ny > M;
+    }
+}
+```