<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();
        int m = grid[0].size();
        set<pair<pair<int, int>, pair<int, int>>> visited;
        queue<vector<int>> fifo;
        fifo.push({0, 0, 0, 0, 1});
        visited.insert({{0, 0}, {0, 1}});
        int currSteps = 0;

        while (!fifo.empty()) {
            int size = fifo.size();
            for (int sz = 0; sz < size; sz++) {
                auto state = fifo.front();
                fifo.pop();

                int currDir = state[0];
                int tailX = state[1];
                int tailY = state[2];
                int headX = state[3];
                int headY = state[4];

                if (tailX == n - 1 && tailY == m - 2 && headX == n - 1 && headY == m - 1) return currSteps;

                if (currDir == 0) {
                    if (headY + 1 < m && grid[tailX][headY + 1] == 0 && grid[headX][headY + 1] == 0 &&
                        visited.find({{tailX, tailY + 1}, {headX, headY + 1}}) == visited.end()) {
                        visited.insert({{tailX, tailY + 1}, {headX, headY + 1}});
                        fifo.push({0, tailX, tailY + 1, headX, headY + 1});
                    }

                    if (headX + 1 < n && grid[headX + 1][tailY] == 0 && grid[headX + 1][headY] == 0 &&
                        visited.find({{tailX + 1, tailY}, {headX + 1, headY}}) == visited.end()) {
                        visited.insert({{tailX + 1, tailY}, {headX + 1, headY}});
                        fifo.push({0, tailX + 1, tailY, headX + 1, headY});
                    }

                    if (headX + 1 < n && grid[headX + 1][headY] == 0 && grid[headX + 1][tailY] == 0 &&
                        visited.find({{tailX, tailY}, {tailX + 1, tailY}}) == visited.end()) {
                        visited.insert({{tailX, tailY}, {tailX + 1, tailY}});
                        fifo.push({1, tailX, tailY, tailX + 1, tailY});
                    }
                }
                else {
                    if (headX + 1 < n && grid[headX + 1][tailY] == 0 && grid[headX + 1][headY] == 0 &&
                        visited.find({{tailX + 1, tailY}, {headX + 1, headY}}) == visited.end()) {
                        visited.insert({{tailX + 1, tailY}, {headX + 1, headY}});
                        fifo.push({1, tailX + 1, tailY, headX + 1, headY});
                    }

                    if (headY + 1 < m && grid[tailX][headY + 1] == 0 && grid[headX][headY + 1] == 0 &&
                        visited.find({{tailX, tailY + 1}, {headX, headY + 1}}) == visited.end()) {
                        visited.insert({{tailX, tailY + 1}, {headX, headY + 1}});
                        fifo.push({1, tailX, tailY + 1, headX, headY + 1});
                    }

                    if (headY + 1 < m && grid[headX][headY + 1] == 0 && grid[tailX][headY + 1] == 0 &&
                        visited.find({{tailX, tailY}, {tailX, tailY + 1}}) == visited.end()) {
                        visited.insert({{tailX, tailY}, {tailX, tailY + 1}});
                        fifo.push({0, tailX, tailY, tailX, tailY + 1});
                    }
                }
            }
            currSteps += 1;
        }
        return -1;
    }
};
35900