<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:
    def minimumMoves(self, grid: List[List[int]]) -> int:
        side, queue = len(grid), deque([[(0, 0), (0, 1), 0]])
        visited = {((0, 0), (0, 1))}
        directions = [[(0, 1), (0, 1)], [(1, 0), (1, 0)], 
                      [(0, 0), (1, -1)], [(0, 0), (-1, 1)]]

        def validate(row1: int, col1: int, row2: int, col2: int, dirIndex: int) -> bool:
            if not (0 <= row1 < side and 0 <= col1 < side and 0 <= row2 < side and 0 <= col2 < side):
                return False
            if grid[row1][col1] != 0 or grid[row2][col2] != 0:
                return False
            if dirIndex >= 2:  # Edge Case 1
                if grid[row1 + 1][col1 + 1] == 1:
                    return False
            return True
        
        while queue:
            (row1, col1), (row2, col2), step = queue.popleft()
            if row1 == side - 1 and col1 == side - 2 and row2 == side - 1 and col2 == side - 1:
                return step
            for dirIndex in range(len(directions)):
                if dirIndex == 2:
                    if row1 != row2:
                        continue
                if dirIndex == 3:
                    if col1 != col2:
                        continue
                (drow1, dcol1), (drow2, dcol2) = directions[dirIndex]
                newRow1, newCol1 = row1 + drow1, col1 + dcol1
                newRow2, newCol2 = row2 + drow2, col2 + dcol2
                if validate(newRow1, newCol1, newRow2, newCol2, dirIndex) and ((newRow1, newCol1), (newRow2, newCol2)) not in visited:
                    visited.add(((newRow1, newCol1), (newRow2, newCol2)))
                    queue.append(((newRow1, newCol1), (newRow2, newCol2), step + 1))
        return -1
20100