洪水填充板子题：bfs+区域标记

int dx[4] = { 0,0,-1,1 };
int dy[4] = { 1,-1,0,0 };

void solveA() {
	int t = 1;
	et(t) {
		int n, m; cin >> n >> m;
		vector<vector<int>>matrix(n + 1, vector<int>(n + 1));
		for (int i = 1; i <= n; i++) {
			string str; cin >> str;
			for (int j = 1; j <= n; j++) {
				matrix[i][j] = str[j - 1] + '0';
			}

		}

		int cnt = 1;
		unordered_map<int, int>hash;
		vector<vector<int>>mask(n + 1, vector<int>(n + 1,0));
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= n; j++) {
				if (mask[i][j] == 0) {
					queue<pair<int,int>>q;
					int num = 1;
					q.push({ i,j });
					mask[i][j] = cnt;
					
					while (!q.empty()) {
						int top_i = q.front().first;
						int top_j = q.front().second;
						q.pop();

						for (int dic = 0; dic < 4; dic++) {
							int ni = top_i + dy[dic];
							int nj = top_j + dx[dic];

							if (ni >= 1 && ni <= n && nj >= 1 && nj <= n&&mask[ni][nj]==0) {
								if (matrix[top_i][top_j] != matrix[ni][nj]) {
									q.push({ ni,nj });
									mask[ni][nj] = cnt;
									num++;
								}
							}
						}
					}
					hash[cnt] = num;
					cnt++;
				}
			}
		}

		for (int i = 0; i < m; i++) {
			int ni, nj; cin >> ni >> nj;
			cout << hash[mask[ni][nj]] << endl;
		}
	}
}