[20250311] BOJ / P5 / 배열에서 이동 / 권혁준

khj20006/202503/11 BOJ P5 배열에서 이동.md

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+```java
+
+import java.util.*;
+import java.io.*;
+
+
+class Main {
+
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st;
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static int nextInt() {return Integer.parseInt(st.nextToken());}
+	static long nextLong() {return Long.parseLong(st.nextToken());}
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+
+	// Additional field
+
+	static int N;
+	static int[][] A;
+
+	static int[] dx = {1,0,-1,0};
+	static int[] dy = {0,1,0,-1};
+
+	public static void main(String[] args) throws Exception {
+
+		ready();
+		solve();
+
+		bwEnd();
+
+	}
+
+	static void ready() throws Exception{
+
+		N = Integer.parseInt(br.readLine());
+		A = new int[N][N];
+		for(int i=0;i<N;i++) {
+			nextLine();
+			for(int j=0;j<N;j++) A[i][j] = nextInt();
+		}
+
+	}
+
+	static void solve() throws Exception{
+
+		int ans = Integer.MAX_VALUE;
+		while(A[0][0] >= 0) {
+			ans = Math.min(ans, findMin());
+			reduce();
+		}
+		bw.write(ans + "\n");
+
+	}
+
+	static void reduce() {
+		for(int i=0;i<N;i++) for(int j=0;j<N;j++) A[i][j]--;
+	}
+
+	static int findMin() {
+
+		int s = 0, e = 200, m = (s+e)>>1;
+		// m이하인 칸들로만 도달할 수 있는지?
+		while(s<e) {
+			if(bfs(m)) e = m;
+			else s = m+1;
+			m = (s+e)>>1;
+		}
+		return m;
+
+	}
+
+	// limit 제한 내에서의 bfs
+	static boolean bfs(int limit) {
+
+		if(A[0][0] > limit) return false;
+
+		Queue<int[]> Q = new LinkedList<>();
+		boolean[][] vis = new boolean[N][N];
+		Q.offer(new int[] {0,0});
+		vis[0][0] = true;
+		while(!Q.isEmpty()) {
+
+			int[] now = Q.poll();
+			int x = now[0], y = now[1];
+			if(x == N-1 && y == N-1) return true;
+			for(int i=0;i<4;i++) {
+				int xx = x+dx[i], yy = y+dy[i];
+				if(safe(xx,yy) && A[xx][yy] <= limit && A[xx][yy] >= 0 && !vis[xx][yy]) {
+					vis[xx][yy] = true;
+					Q.offer(new int[] {xx,yy});
+				}
+			}
+
+		}
+
+		return false;
+
+	}
+
+	static boolean safe(int x, int y) {
+		return 0<=x&&x<N && 0<=y&&y<N;
+	}
+
+}
+
+```