<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) {
        queue<pair<pair<int,int>,int>> q;
        vector<vector<vector<int>>> vis(grid.size(),vector<vector<int>>(grid.size(),vector<int>(2,0)));
        q.push({{0,1},0});
        vis[0][1][0] = 1;
        int steps=0;
        while(!q.empty()){
            int sz = q.size();
            for(int i=0;i<sz;i++){
                int x = q.front().first.first;
                int y = q.front().first.second;
                int pos = q.front().second;
                //cout<<x<<" "<<y<<" "<<steps<<endl;
                if(x==grid.size()-1 && y==grid.size()-1 && pos==0) return steps;
                q.pop();
                if(pos==0){
                    if(y+1<grid.size() && grid[x][y+1]==0 && !vis[x][y+1][pos]){
                        q.push({{x,y+1},pos});
                        vis[x][y+1][pos] = 1;
                    }
                    if(x+1<grid.size() && grid[x+1][y]==0 && y-1>=0 && grid[x+1][y-1]==0 && !vis[x+1][y][pos]){
                        q.push({{x+1,y},pos});
                        vis[x+1][y][pos] = 1;
                    }
                    if(x+1<grid.size() && y-1>=0 && grid[x+1][y-1]==0 && grid[x+1][y]==0 && !vis[x+1][y-1][1]){
                        q.push({{x+1,y-1},1});
                        vis[x+1][y-1][1] = 1;
                    }
                }
                else{
                    if(y+1<grid.size() && grid[x][y+1]==0 && x-1>=0 && grid[x-1][y+1]==0 && !vis[x][y+1][pos]){
                        q.push({{x,y+1},pos});
                        vis[x][y+1][pos] = 1;
                    }
                    if(x+1<grid.size() && grid[x+1][y]==0 && !vis[x+1][y][pos]){
                        q.push({{x+1,y},pos});
                        vis[x+1][y][pos] = 1;
                    }
                    if(y+1<grid.size() && x-1>=0 && grid[x-1][y+1]==0 && grid[x][y+1]==0 && !vis[x-1][y+1][0]){
                        q.push({{x-1,y+1},0});
                        vis[x-1][y+1][0] = 1;
                    }
                }
            }
            steps++;
        }
        return -1;
    }
};
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