2019汇顶科技校招笔试——池塘个数/岛屿个数

池塘个数/岛屿个数

#include<iostream>
#include<vector>
#include<queue>
#include<algorithm>

using namespace std;

bool isCheck(int i, int j, int M, int N)
{
	if (i >= 0 && i < M && j >= 0 && j < N)
		return true;
	else
		return false;
}

void bfs(vector<vector<int>> &ivec, vector<vector<bool>> &flag, vector<int> &a, vector<int> &b, int x, int y, int M, int N)
{
	queue<pair<int,int>> q;
	q.push(make_pair(x, y));
	flag[x][y] = false;
	while (!q.empty())
	{
		pair<int, int> p = q.front();
		q.pop();
		for (int i = 0; i < 4; i++)
		{
			int newX = p.first + a[i];
			int newY = p.second + b[i];
			if (isCheck(newX, newY, M, N) && ivec[newX][newY] == 1 && flag[newX][newY])
			{
				q.push({ newX, newY });
				flag[newX][newY] = false;
			}
		}
	}
}

int main()
{
	int M, N;
	while (cin >> M >> N)
	{
		int num;
		vector<vector<int>> ivec(M, vector<int>(N, 0));
		for (int i = 0; i < M; i++)
		{
			for (int j = 0; j < N; j++)
				cin >> ivec[i][j];
		}
		vector<vector<bool>> flag(M, vector<bool>(N, true));
		vector<int> a = { 1, -1, 0, 0 };
		vector<int> b = { 0, 0, 1, -1 };
		int count = 0;
		for (int i = 0; i < M; i++)
		{
			for (int j = 0; j < N; j++)
			{
				if (ivec[i][j] == 1 && flag[i][j])
				{
					bfs(ivec, flag, a, b, i, j, M, N);
					count++;
				}
			}
		}
		cout << count << endl;
	}
	return 0;
}