Merge pull request #1470 from AlgorithmWithGod/Ukj0ng

[20251121] BOJ / P5 / 배열에서 이동

Author: ShinHeeEul

Ukj0ng/202511/21 BOJ P5 배열에서 이동.md

@@ -0,0 +1,108 @@
+```
+import java.io.*;
+import java.util.*;
+
+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 int[][] arr;
+    private static boolean[][] visited;
+    private static int N, max, min;
+    public static void main(String[] args) throws IOException {
+        init();
+
+        int answer = binarySearch();
+
+        bw.write(answer + "\n");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        N = Integer.parseInt(br.readLine());
+        max = -1;
+        min = 201;
+
+        arr = new int[N][N];
+        visited = new boolean[N][N];
+
+        for (int i = 0; i < N; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+
+            for (int j = 0; j < N; j++) {
+                arr[i][j] = Integer.parseInt(st.nextToken());
+                max = Math.max(max, arr[i][j]);
+                min = Math.min(min, arr[i][j]);
+            }
+        }
+    }
+
+    private static int binarySearch() {
+        int left = 0;
+        int right = 200;
+        int result = 200;
+
+        while (left <= right) {
+            int mid = left + (right - left) / 2;
+
+            if (valid(mid)) {
+                result = mid;
+                right = mid-1;
+            } else {
+                left = mid+1;
+            }
+        }
+
+        return result;
+    }
+
+    private static boolean valid(int diff) {
+        for (int i = min; i <= max; i++) {
+            int temp = i + diff;
+
+            if (arr[0][0] < i || arr[0][0] > temp || arr[N-1][N-1] < i || arr[N-1][N-1] > temp) continue;
+
+            if (canReach(i, temp)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private static boolean canReach(int min, int max) {
+        Queue<int[]> q = new ArrayDeque<>();
+        for (int i = 0; i < N; i++) {
+            Arrays.fill(visited[i], false);
+        }
+        visited[0][0] = true;
+        q.add(new int[]{0, 0});
+
+        while (!q.isEmpty()) {
+            int[] current = q.poll();
+
+            if (current[0] == N-1 && current[1] == N-1) {
+                return true;
+            }
+
+            for (int i = 0; i < 4; i++) {
+                int nx = current[0] + dx[i];
+                int ny = current[1] + dy[i];
+
+                if (OOB(nx, ny) || arr[nx][ny] > max || arr[nx][ny] < min || visited[nx][ny]) continue;
+                visited[nx][ny] = true;
+                q.add(new int[] {nx, ny});
+            }
+        }
+
+        return false;
+    }
+
+    private static boolean OOB(int nx, int ny) {
+        return nx < 0 || nx > N-1 || ny < 0 || ny > N-1;
+    }
+}
+```