<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:
    vector<vector<int>> grid;
    int n;
    bool rotate(int x, int y){
        return x < n - 1 && y < n - 1 && (grid[x+1][y] + grid[x][y+1] + grid[x+1][y+1] == 0);
    }
    bool godown(int x, int y, bool vertical){
        if(vertical)
            return x+2 < n && grid[x+2][y]==0;
        else
            return x+1 < n && grid[x+1][y] + grid[x+1][y+1]==0;
    }
    bool goright(int x, int y, bool vertical){
        if(vertical)
            return y+1 < n && grid[x][y+1] + grid[x+1][y+1]==0;
        else
            return y+2 < n && grid[x][y+2]==0;
    }
    int minimumMoves(vector<vector<int>>& grid) {
        this->grid = grid;
        this->n = grid.size();
        queue<array<int, 3>> q;
        q.push({0, 0, false});
        int steps = 0;
        while(!q.empty()){
            int size = q.size();
            while(size--){
                auto a = q.front();
                q.pop();
                if(a[0] == n-1 && a[1] == n-2)
                    return steps;
                if((grid[a[0]][a[1]] & (a[2] ? 2 : 4)) == 0){
                    grid[a[0]][a[1]] = grid[a[0]][a[1]] | (a[2] ? 2 : 4);
                    if(godown(a[0], a[1], a[2]))
                        q.push({a[0]+1, a[1], a[2]});
                    if(goright(a[0], a[1], a[2]))
                        q.push({a[0], a[1]+1, a[2]});
                    if(rotate(a[0], a[1]))
                        q.push({a[0], a[1], 1-a[2]});
                }
            }
            steps++;
        }
        return -1;
    }
};
18800