<p>Given a 2D&nbsp;<code>grid</code> consists of <code>0s</code> (land)&nbsp;and <code>1s</code> (water).&nbsp; An <em>island</em> is a maximal 4-directionally connected group of <code><font face="monospace">0</font>s</code> and a <em>closed island</em>&nbsp;is an island <strong>totally</strong>&nbsp;(all left, top, right, bottom) surrounded by <code>1s.</code></p>

<p>Return the number of <em>closed islands</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_3_1610.png" style="width: 240px; height: 120px;" /></p>

<pre>
<strong>Input:</strong> grid = [[1,1,1,1,1,1,1,0],[1,0,0,0,0,1,1,0],[1,0,1,0,1,1,1,0],[1,0,0,0,0,1,0,1],[1,1,1,1,1,1,1,0]]
<strong>Output:</strong> 2
<strong>Explanation:</strong> 
Islands in gray are closed because they are completely surrounded by water (group of 1s).</pre>

<p><strong class="example">Example 2:</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_4_1610.png" style="width: 160px; height: 80px;" /></p>

<pre>
<strong>Input:</strong> grid = [[0,0,1,0,0],[0,1,0,1,0],[0,1,1,1,0]]
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1,1,1,1,1,1,1],
&nbsp;              [1,0,0,0,0,0,1],
&nbsp;              [1,0,1,1,1,0,1],
&nbsp;              [1,0,1,0,1,0,1],
&nbsp;              [1,0,1,1,1,0,1],
&nbsp;              [1,0,0,0,0,0,1],
               [1,1,1,1,1,1,1]]
<strong>Output:</strong> 2
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= grid.length, grid[0].length &lt;= 100</code></li>
	<li><code>0 &lt;= grid[i][j] &lt;=1</code></li>
</ul>

class Solution {
public:
    int arr[100][100];
    bool vis[100][100];
    int n,m;
    bool ans;
    bool valid(int i,int j){
        if(i<0 || i>=n || j<0 || j>=m)return false;
        else return true;
    }
    vector<pair<int,int>>d={{0,1},{0,-1},{1,0},{-1,0}};
    void count(int s1,int s2){
        vis[s1][s2]=true;
        for(int i=0;i<4;i++){
            int x=s1+d[i].first;
            int y=s2+d[i].second;
            if(!valid(x,y))ans=false;
            if(valid(x,y) && !vis[x][y] && arr[x][y]==0){
                count(x,y);
            }
        }
    }
    int closedIsland(vector<vector<int>>& grid) {
        n=grid.size();
        m=grid[0].size();
        memset(arr,1,sizeof(arr));
        memset(vis,false,sizeof(vis));
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                arr[i][j]=grid[i][j];
            }
        }
        int cnt=0;
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
               if(!vis[i][j] && arr[i][j]==0){
                    ans=true;
                   count(i,j);
                   if(ans)cnt++;
                }
            }
        }
        return cnt;
    }
};
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