가장 낮은 높이 -1 부터 가장 높은 높이까지의 경우의 수를 따져서 최대 안전영역을 출력하면됩니다.
1.DFS 풀이 방법
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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
public class Main2468_안전영역_DFS {
private static int[][] map;
private static int N;
private static int maxNum;
private static int mapMaxNum;
private static int mapMinNum;
private static boolean[][] visited;
static int[] dx = {-1, 1 , 0 , 0};
static int[] dy = {0 , 0 , -1 , 1};
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
N = Integer.parseInt(br.readLine());
map = new int[N][N];
for (int i = 0; i < N; i++) {
StringTokenizer st = new StringTokenizer(br.readLine(), " ");
for (int j = 0; j < N; j++) {
map[i][j] = Integer.parseInt(st.nextToken());
}
}
maxNum = Integer.MIN_VALUE;
mapMaxNum = Integer.MIN_VALUE;
mapMinNum = Integer.MAX_VALUE;
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
if(mapMaxNum < map[i][j]) {
mapMaxNum = map[i][j];
}
if(mapMinNum > map[i][j]) {
mapMinNum = map[i][j];
}
}
}
int result ;
for (int i = mapMinNum; i < mapMaxNum; i++) {
result = 0;
visited = new boolean[N][N];
for (int j = 0; j < N; j++) {
for (int k = 0; k < N; k++) {
if(map[j][k] <=i) {
map[j][k] = 0;
}
}
}
for (int j = 0; j < N; j++) {
for (int k = 0; k < N; k++) {
if(map[j][k] !=0 && !visited[j][k]) {
visited[j][k] =true;
result++;
dfs(j,k);
}
}
}
maxNum = maxNum < result ? result: maxNum;
}
System.out.println(maxNum);
}// end of main
public static void dfs(int x, int y) {
for (int i = 0; i < dx.length; i++) {
int nx = x + dx[i];
int ny = y + dy[i];
if(nx>=0 && ny >=0 && nx < N && ny < N && !visited[nx][ny] && map[nx][ny] !=0) {
visited[nx][ny] = true;
dfs(nx,ny);
}
}
}
}// end of class
|
cs |
2.BFS 풀이 방법
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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;
public class Main2468_안전영역_BFS {
private static int[][] map;
private static int N;
private static int maxNum;
private static int mapMaxNum;
private static int mapMinNum;
private static boolean[][] visited;
static int[] dx = {-1, 1 , 0 , 0};
static int[] dy = {0 , 0 , -1 , 1};
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
N = Integer.parseInt(br.readLine());
map = new int[N][N];
for (int i = 0; i < N; i++) {
StringTokenizer st = new StringTokenizer(br.readLine(), " ");
for (int j = 0; j < N; j++) {
map[i][j] = Integer.parseInt(st.nextToken());
}
}
maxNum = Integer.MIN_VALUE;
mapMaxNum = Integer.MIN_VALUE;
mapMinNum = Integer.MAX_VALUE;
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
if(mapMaxNum < map[i][j]) {
mapMaxNum = map[i][j];
}
if(mapMinNum > map[i][j]) {
mapMinNum = map[i][j];
}
}
}
int result ;
for (int i = mapMinNum-1; i <= mapMaxNum; i++) {
result = 0;
visited = new boolean[N][N];
for (int j = 0; j < N; j++) {
for (int k = 0; k < N; k++) {
if(map[j][k] <=i) {
map[j][k] = 0;
}
}
}
for (int j = 0; j < N; j++) {
for (int k = 0; k < N; k++) {
if(map[j][k] !=0 && !visited[j][k]) {
result ++;
bfs(j,k);
}
}
}
maxNum = maxNum < result ? result: maxNum;
}
System.out.println(maxNum);
}// end of main
public static void bfs(int x, int y) {
Queue<Pair> q = new LinkedList<>();
visited[x][y] = true;
q.add(new Pair(x, y));
while(!q.isEmpty()) {
Pair p = q.poll();
for (int i = 0; i < dx.length; i++) {
int nx = p.x + dx[i];
int ny = p.y + dy[i];
if(nx >=0 && ny >=0 && nx < N && ny < N && map[nx][ny] !=0 && !visited[nx][ny]) {
visited[nx][ny] = true;
q.add(new Pair(nx, ny));
}
}
}
}
static class Pair{
int x;
int y;
public Pair(int x, int y) {
super();
this.x = x;
this.y = y;
}
}
}
|
cs |
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