<p>An <code>n x n</code> grid is composed of <code>1 x 1</code> squares where each <code>1 x 1</code> square consists of a <code>&#39;/&#39;</code>, <code>&#39;\&#39;</code>, or blank space <code>&#39; &#39;</code>. These characters divide the square into contiguous regions.</p>

<p>Given the grid <code>grid</code> represented as a string array, return <em>the number of regions</em>.</p>

<p>Note that backslash characters are escaped, so a <code>&#39;\&#39;</code> is represented as <code>&#39;\\&#39;</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/1.png" style="width: 200px; height: 200px;" />
<pre>
<strong>Input:</strong> grid = [&quot; /&quot;,&quot;/ &quot;]
<strong>Output:</strong> 2
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/2.png" style="width: 200px; height: 198px;" />
<pre>
<strong>Input:</strong> grid = [&quot; /&quot;,&quot;  &quot;]
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/4.png" style="width: 200px; height: 200px;" />
<pre>
<strong>Input:</strong> grid = [&quot;/\\&quot;,&quot;\\/&quot;]
<strong>Output:</strong> 5
<strong>Explanation: </strong>Recall that because \ characters are escaped, &quot;\\/&quot; refers to \/, and &quot;/\\&quot; refers to /\.
</pre>

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

<ul>
	<li><code>n == grid.length == grid[i].length</code></li>
	<li><code>1 &lt;= n &lt;= 30</code></li>
	<li><code>grid[i][j]</code> is either <code>&#39;/&#39;</code>, <code>&#39;\&#39;</code>, or <code>&#39; &#39;</code>.</li>
</ul>

class Solution {
public:
    void colourNeighbours(vector<string>& grid, vector<vector<vector<int>>>& my_grid, int i, int j, int colour, int prev) {
        int n = grid.size();
        switch (grid[i][j]) {
            case ' ':
                if (!my_grid[i][j][0]) {
                    my_grid[i][j] = vector<int>(4,colour);
                    if (i > 0) {
                        colourNeighbours(grid, my_grid, i-1, j, colour, 1);
                    }
                    if (j > 0) {
                        colourNeighbours(grid, my_grid, i, j-1, colour, 0);
                    }
                    if (j < n - 1) {
                        colourNeighbours(grid, my_grid, i, j+1, colour, 2);
                    }
                    if (i < n - 1) {
                        colourNeighbours(grid, my_grid, i+1, j, colour, 3);
                    }
                }
                break;
            case '/':
                if (prev == 0 || prev == 1) {
                    if (!my_grid[i][j][3]) {
                        my_grid[i][j][3] = colour;
                        my_grid[i][j][2] = colour;
                        if (j < n - 1) {
                            colourNeighbours(grid, my_grid, i, j+1, colour, 2);
                        }
                        if (i < n - 1) {
                            colourNeighbours(grid, my_grid, i+1, j, colour, 3);
                        }
                    }
                }
                else {
                    if (!my_grid[i][j][0]) {
                        my_grid[i][j][0] = colour;
                        my_grid[i][j][1] = colour;
                        if (i > 0) {
                            colourNeighbours(grid, my_grid, i-1, j, colour, 1);
                        }
                        if (j > 0) {
                            colourNeighbours(grid, my_grid, i, j-1, colour, 0);
                        }
                    }
                }
                break;
            case '\\':
                if (prev == 2 || prev == 1) {
                    if (!my_grid[i][j][3]) {
                        my_grid[i][j][3] = colour;
                        my_grid[i][j][0] = colour;
                        if (j > 0) {
                            colourNeighbours(grid, my_grid, i, j-1, colour, 0);
                        }
                        if (i < n - 1) {
                            colourNeighbours(grid, my_grid, i+1, j, colour, 3);
                        }
                    }
                }
                else {
                    if (!my_grid[i][j][1]) {
                        my_grid[i][j][1] = colour;
                        my_grid[i][j][2] = colour;
                        if (i > 0) {
                            colourNeighbours(grid, my_grid, i-1, j, colour, 1);
                        }
                        if (j < n - 1) {
                            colourNeighbours(grid, my_grid, i, j+1, colour, 2);
                        }
                    }
                }
                break;
        }
    }
    int regionsBySlashes(vector<string>& grid) {
        int n = grid.size();
        vector<vector<vector<int>>> paintRegions(n, vector<vector<int>>(n, vector<int>(4,0)));
        int colours = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                switch (grid[i][j]) {
                    case ' ':
                        if (paintRegions[i][j][0]) {
                            break;
                        }
                        colours++;
                        paintRegions[i][j] = vector<int>(4,colours);
                        if (j < n - 1) {
                            colourNeighbours(grid, paintRegions, i, j+1, colours, 2);
                        }
                        if (i < n - 1) {
                            colourNeighbours(grid, paintRegions, i+1, j, colours, 3);
                        }
                        break;
                    case '/':
                        if (!paintRegions[i][j][0]) {
                            colours++;
                            paintRegions[i][j][0] = colours;
                            paintRegions[i][j][1] = colours;
                            if (i > 0) {
                                colourNeighbours(grid, paintRegions, i-1, j, colours, 1);
                            }
                            if (j > 0) {
                                colourNeighbours(grid, paintRegions, i, j-1, colours, 0);
                            }
                        }
                        if (!paintRegions[i][j][2]) {
                            colours++;
                            paintRegions[i][j][2] = colours;
                            paintRegions[i][j][3] = colours;
                            if (j < n - 1) {
                                colourNeighbours(grid, paintRegions, i, j+1, colours, 2);
                            }
                            if (i < n - 1) {
                                colourNeighbours(grid, paintRegions, i+1, j, colours, 3);
                            }
                        }
                        break;
                    case '\\':
                        if (!paintRegions[i][j][0]) {
                            colours++;
                            paintRegions[i][j][0] = colours;
                            paintRegions[i][j][3] = colours;
                            if (j > 0) {
                                colourNeighbours(grid, paintRegions, i, j-1, colours, 0);
                            }
                            if (i < n - 1) {
                                colourNeighbours(grid, paintRegions, i+1, j, colours, 3);
                            }
                        }
                        if (!paintRegions[i][j][2]) {
                            colours++;
                            paintRegions[i][j][1] = colours;
                            paintRegions[i][j][2] = colours;
                            if (j < n - 1) {
                                colourNeighbours(grid, paintRegions, i, j+1, colours, 2);
                            }
                            if (i > 0) {
                                colourNeighbours(grid, paintRegions, i-1, j, colours, 1);
                            }
                        }
                        break;
                }
            }
        }
        for (auto& i: paintRegions) {
            for (auto& j: i) {
                cout << j[0] << "---" << j[1] << "---" << j[2] << "---" << j[3] << endl;
            }
        }
        return colours;
    }
};
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