[Algorithm] Baekjoon 2468번 : 안전 영역

https://www.acmicpc.net/problem/2468

2468번: 안전 영역

int n;
 
int arr[101][101];
int tempMap[101][101];
int dir[4][2] = { {-1,0}, {1,0}, {0,-1}, {0,1} };
bool visited[101][101];
 
struct Node
{
    int y;
    int x;
};
 
 
void BFS(int startY, int startX, int maxHeight) // maxHeight 초과의 영역 개수.
{
    queue<Node> q;
    q.push({ startY, startX });
    visited[startY][startX] = true;
      
    while (!q.empty())
    {
        int curY = q.front().y;
        int curX = q.front().x;
        q.pop();
 
        for (int i = 0; i < 4; ++i)
        {
            int nextY = curY + dir[i][0];
            int nextX = curX + dir[i][1];
 
            if (nextY < 0 || nextY >= n) continue;
            if (nextX < 0 || nextX >= n) continue;
            if (tempMap[nextY][nextX] <= maxHeight) continue; 
            if (visited[nextY][nextX]) continue;
            
            visited[nextY][nextX] = true;
            q.push({ nextY,nextX });
        }
    }
}
 
int getSafeZoneCount(int maxHeight) // maxHeight 미만은 물에 잠김.
{
    memcpy(tempMap, arr, sizeof(tempMap));
    memset(visited, false, sizeof(visited));
    int safeCount = 0;
 
    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            if (visited[i][j] || tempMap[i][j] <= maxHeight) continue;
            BFS(i, j, maxHeight);
            ++safeCount;
        }
    }
 
    return safeCount;
}
 
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
 
    cin >> n;
    int result = 0;
 
    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            cin >> arr[i][j];
        }
    }
 
    for (int i = 0; i <= 100; ++i)
    {
        result = max(result, getSafeZoneCount(i));
    }
    
    cout << result;
}