<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 {
private:
    int x_dir[4] = {-1, 0, 0, 1};
    int y_dir[4] = {0, -1, 1, 0};
    void exploreHelper(vector<vector<char>>& intGrid, int i, int j) {
        for (int k = 0; k < 4; k++) {
            if (i+x_dir[k] < 0 || i+x_dir[k] >= intGrid.size()) {
                continue;
            }
            if (j+y_dir[k] < 0 || j+y_dir[k] >= intGrid[0].size()) {
                continue;
            }
            if (intGrid[i+x_dir[k]][j+y_dir[k]] == '0') {
                intGrid[i+x_dir[k]][j+y_dir[k]] = '2';
                exploreHelper(intGrid, i+x_dir[k], j+y_dir[k]);
            }
        }
    }

    int explore(vector<vector<char>>& intGrid) {
        int numIslands = 0;
        for (int i = 0; i < intGrid.size(); i++) {
            for (int j = 0; j < intGrid[i].size(); j++) {
                if (intGrid[i][j] == '0') {
                    intGrid[i][j] = '2';
                    exploreHelper(intGrid, i, j);
                    numIslands++;
                }
            }
        }
        return numIslands;
    }
public:
    int regionsBySlashes(vector<string>& grid) {
        vector<vector<char>> intGrid(grid.size() * 3, vector<char>(grid[0].size() * 3, '0'));
        int row = 0, col = 0;

        for (auto& s: grid) {
            col = 0;
            for (auto& c: s) {
                if (c == '/') {
                    intGrid[row+0][col+0] = '0'; intGrid[row+0][col+1] = '0'; intGrid[row+0][col+2] = '1';
                    intGrid[row+1][col+0] = '0'; intGrid[row+1][col+1] = '1'; intGrid[row+1][col+2] = '0';
                    intGrid[row+2][col+0] = '1'; intGrid[row+2][col+1] = '0'; intGrid[row+2][col+2] = '0';
                } else if (c == '\\') {
                    intGrid[row+0][col+0] = '1'; intGrid[row+0][col+1] = '0'; intGrid[row+0][col+2] = '0';
                    intGrid[row+1][col+0] = '0'; intGrid[row+1][col+1] = '1'; intGrid[row+1][col+2] = '0';
                    intGrid[row+2][col+0] = '0'; intGrid[row+2][col+1] = '0'; intGrid[row+2][col+2] = '1';
                }
                col += 3;
            }
            row += 3;
        }

        int numIslands = explore(intGrid);
        return numIslands;
    }
};
12396