<p>In an&nbsp;<code>n*n</code>&nbsp;grid, there is a snake that spans 2 cells and starts moving from the top left corner at <code>(0, 0)</code> and <code>(0, 1)</code>. The grid has empty cells represented by zeros and blocked cells represented by ones. The snake wants to reach the lower right corner at&nbsp;<code>(n-1, n-2)</code>&nbsp;and&nbsp;<code>(n-1, n-1)</code>.</p>

<p>In one move the snake can:</p>

<ul>
	<li>Move one cell to the right&nbsp;if there are no blocked cells there. This move keeps the horizontal/vertical position of the snake as it is.</li>
	<li>Move down one cell&nbsp;if there are no blocked cells there. This move keeps the horizontal/vertical position of the snake as it is.</li>
	<li>Rotate clockwise if it&#39;s in a horizontal position and the two cells under it are both empty. In that case the snake moves from&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r, c+1)</code>&nbsp;to&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r+1, c)</code>.<br />
	<img alt="" src="https://assets.leetcode.com/uploads/2019/09/24/image-2.png" style="width: 300px; height: 134px;" /></li>
	<li>Rotate counterclockwise&nbsp;if it&#39;s in a vertical position and the two cells to its right are both empty. In that case the snake moves from&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r+1, c)</code>&nbsp;to&nbsp;<code>(r, c)</code>&nbsp;and&nbsp;<code>(r, c+1)</code>.<br />
	<img alt="" src="https://assets.leetcode.com/uploads/2019/09/24/image-1.png" style="width: 300px; height: 121px;" /></li>
</ul>

<p>Return the minimum number of moves to reach the target.</p>

<p>If there is no way to reach the target, return&nbsp;<code>-1</code>.</p>

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

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/09/24/image.png" style="width: 400px; height: 439px;" /></strong></p>

<pre>
<strong>Input:</strong> grid = [[0,0,0,0,0,1],
               [1,1,0,0,1,0],
&nbsp;              [0,0,0,0,1,1],
&nbsp;              [0,0,1,0,1,0],
&nbsp;              [0,1,1,0,0,0],
&nbsp;              [0,1,1,0,0,0]]
<strong>Output:</strong> 11
<strong>Explanation:
</strong>One possible solution is [right, right, rotate clockwise, right, down, down, down, down, rotate counterclockwise, right, down].
</pre>

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

<pre>
<strong>Input:</strong> grid = [[0,0,1,1,1,1],
&nbsp;              [0,0,0,0,1,1],
&nbsp;              [1,1,0,0,0,1],
&nbsp;              [1,1,1,0,0,1],
&nbsp;              [1,1,1,0,0,1],
&nbsp;              [1,1,1,0,0,0]]
<strong>Output:</strong> 9
</pre>

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

<ul>
	<li><code>2 &lt;= n &lt;= 100</code></li>
	<li><code>0 &lt;= grid[i][j] &lt;= 1</code></li>
	<li>It is guaranteed that the snake starts at empty cells.</li>
</ul>

class Solution {
public:
    
    int minimumMoves(vector<vector<int>>& grid) {
    
        int n=grid.size();

        queue<array<int,4>> q;
        
        q.push({0,0,0,1});
        
        int ans=0;
        
        set<array<int,4>> st;
        
        st.insert({0,0,0,1});
        
        while(!q.empty()){
            
        
            int sz=q.size();
            
            while(sz--){
                array<int,4> ar=q.front();
                
                q.pop();
                
                if(ar[0]==n-1 and ar[1]==n-2 and ar[2]==n-1 and ar[3]==n-1)
                    return ans;
                
                if(ar[1]!=ar[3]){
                    if(ar[3]+1<n and grid[ar[2]][ar[3]+1]==0 and !st.count({ar[0],ar[1]+1,ar[2],ar[3]+1}))
                    {
                        q.push({ar[0],ar[1]+1,ar[2],ar[3]+1});
                        st.insert({ar[0],ar[1]+1,ar[2],ar[3]+1});
                    }
                    
                    if(ar[0]+1<n and grid[ar[0]+1][ar[1]]==0 and grid[ar[2]+1][ar[3]]==0 and !st.count({ar[0]+1,ar[1],ar[2]+1,ar[3]}))
                    {
                        q.push({ar[0]+1,ar[1],ar[2]+1,ar[3]});
                        st.insert({ar[0]+1,ar[1],ar[2]+1,ar[3]});
                    }
                    
                    if(ar[0]+1<n and grid[ar[0]+1][ar[1]]==0  and grid[ar[0]+1][ar[3]]==0 and !st.count({ar[0],ar[1],ar[0]+1,ar[1]}))
                    {
                        q.push({ar[0],ar[1],ar[0]+1,ar[1]});
                        st.insert({ar[0],ar[1],ar[0]+1,ar[1]});
                    }
                }
                else{
                    if(ar[2]+1<n and grid[ar[2]+1][ar[3]]==0 and !st.count({ar[2],ar[3],ar[2]+1,ar[3]}))
                    {
                        q.push({ar[2],ar[3],ar[2]+1,ar[3]});
                        st.insert({ar[2],ar[3],ar[2]+1,ar[3]});
                    }
                    
                    if(ar[1]+1<n and grid[ar[0]][ar[1]+1]==0 and grid[ar[2]][ar[3]+1]==0 and !st.count({ar[0],ar[1]+1,ar[2],ar[3]+1}))
                    {
                        q.push({ar[0],ar[1]+1,ar[2],ar[3]+1});
                        st.insert({ar[0],ar[1]+1,ar[2],ar[3]+1});
                    }
                    
                    if(ar[1]+1<n and grid[ar[0]][ar[1]+1]==0 and grid[ar[2]][ar[1]+1]==0 and !st.count({ar[0],ar[1],ar[0],ar[1]+1}))
                    {
                        q.push({ar[0],ar[1],ar[0],ar[1]+1});
                        st.insert({ar[0],ar[1],ar[0],ar[1]+1});
                    }
                }
                
            }
            ans++;
        }
        
        return -1;
    }
};
23900