[실1] 2468 - 안전 영역

#include <iostream>

using namespace std;
using IntPair = pair<int, int>;

#define MAX 100+1
#define y first
#define x second

IntPair dir[]
{
	{1,  0}, // 상
	{-1, 0}, // 하
	{0, -1}, // 좌
	{0,  1}	 // 우
};

int board[MAX][MAX];
bool vis[MAX][MAX];
int n, ans;

void Reset()
{
	for (int i = 0; i <= n; i++)
	{
		for (int j = 0; j <= n; j++)
			vis[i][j] = false;
	}
}

void DFS(int y, int x, int rain)
{
	vis[y][x] = true;

	for (int i = 0; i < 4; i++)
	{
		int ny = y + dir[i].y, nx = x + dir[i].x;

		if (ny < 1  ||
			ny > n  ||
			nx < 1  ||
			nx > n)
			continue;

		if (!vis[ny][nx] &&
			board[ny][nx] > rain)
			DFS(ny, nx, rain);
	}
}

void Input()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL); cout.tie(NULL);

	cin >> n;

	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= n; j++)
			cin >> board[i][j];
	}
}

void Check()
{
	for (int k = 0; k <= 100; k++)
	{
		int cnt = 0;
		Reset();

		for (int i = 1; i <= n; i++)
		{
			for (int j = 1; j <= n; j++)
			{
				if (board[i][j] > k &&
					!vis[i][j])
				{
					cnt++;
					DFS(i, j, k);
				}
			}
		}
		if (cnt > ans)
			ans = cnt;
	}
}

int main()
{
	Input();
	Check();	
	cout << ans;
}