<p>Given an <code>n x n</code> binary matrix <code>grid</code>, return <em>the length of the shortest <strong>clear path</strong> in the matrix</em>. If there is no clear path, return <code>-1</code>.</p>

<p>A <strong>clear path</strong> in a binary matrix is a path from the <strong>top-left</strong> cell (i.e., <code>(0, 0)</code>) to the <strong>bottom-right</strong> cell (i.e., <code>(n - 1, n - 1)</code>) such that:</p>

<ul>
	<li>All the visited cells of the path are <code>0</code>.</li>
	<li>All the adjacent cells of the path are <strong>8-directionally</strong> connected (i.e., they are different and they share an edge or a corner).</li>
</ul>

<p>The <strong>length of a clear path</strong> is the number of visited cells of this path.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/example1_1.png" style="width: 500px; height: 234px;" />
<pre>
<strong>Input:</strong> grid = [[0,1],[1,0]]
<strong>Output:</strong> 2
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/example2_1.png" style="height: 216px; width: 500px;" />
<pre>
<strong>Input:</strong> grid = [[0,0,0],[1,1,0],[1,1,0]]
<strong>Output:</strong> 4
</pre>

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

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

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

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

class Solution {
public:
bool check(int i , int j ,int n, int m){
    return i>=0 && j>=0 && i<n && j<m;
}
    int shortestPathBinaryMatrix(vector<vector<int>>& grid) {
        int n=grid.size();
        vector<vector<int>>dist(n,vector<int>(n,1e9));
        set<vector<int>>st;
        if(grid[0][0]==1) return -1;
        dist[0][0]=0;
        int dx[8]={0,0,1,-1,-1,-1,1,1};
        int dy[8]={-1,1,0,0,-1,1,1,-1};
        st.insert({0,0,0});
        while(!st.empty()){
            auto it=st.begin();
            int x=(*it)[0];
            int y=(*it)[1];
            int d=(*it)[2];
            for(int i=0;i<8;i++){
                int nx=x+dx[i];
                int ny=y+dy[i];
                if(check(nx,ny,n,n) && grid[nx][ny]!=1 && dist[nx][ny]> 1+d){
                    dist[nx][ny]=d+1;
                    st.insert({nx,ny,dist[nx][ny]});
                }
            }
            st.erase(it);
        }

        return dist[n-1][n-1]==1e9?-1:dist[n-1][n-1]+1;
    }
};
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