안전영역

#include<iostream>
#include<cstdio>
#include<queue>
#include<utility>

using namespace std;

int N;
int a[100][100];
bool d[100][100];
int dx[] = { 0,0,1,-1 };
int dy[] = { 1,-1,0,0 };
int MAX;

void bfs(int x, int y, int h) {
	queue<pair<int, int>> q;
	q.push(make_pair(x, y));
	d[x][y] = true;
	while (!q.empty()) {
		x = q.front().first; y = q.front().second;
		q.pop();
		for (int i = 0; i < 4; i++) {
			int nx = x + dx[i]; int ny = y + dy[i];
			if (nx < N && nx >= 0 && ny < N && ny >= 0) {
				if (d[nx][ny] == false) {
					if (a[nx][ny] > h)
					{
						q.push(make_pair(nx, ny));
						d[nx][ny] = true;
					}
				}
			}
		}
	}
}

void initial() {
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			d[i][j] = false;
		}
	}
}

bool check(int no) {
	int alp = 0;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			if (a[i][j] <= no) {
				alp += 1;
			}
		}
	}
	if (alp == N * N) return false;
	else return true;
}

int main() {
	scanf("%d", &N);
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			scanf("%d", &a[i][j]);
		}
	}

	for (int i = 0; i <= 100; i++) {
		int cnt = 0;
		int height = i;
		for (int j = 0; j < N; j++) {
			for (int k = 0; k < N; k++) {
				if (d[j][k] == false) {
					if (a[j][k] > height) {
						bfs(j, k, height);
						cnt++;
						
					}
				}
			}
		}
		initial();
		if (cnt > MAX) MAX = cnt;
	}
	printf("%d\n", MAX);

	return 0;
}

졸려서그런지 조건하나빼먹어서 런타임에러만 몇번을 했는지.. 전형적인 BFS문제