<p>You are given an integer <code>n</code>. You have an <code>n x n</code> binary grid <code>grid</code> with all values initially <code>1</code>&#39;s except for some indices given in the array <code>mines</code>. The <code>i<sup>th</sup></code> element of the array <code>mines</code> is defined as <code>mines[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> where <code>grid[x<sub>i</sub>][y<sub>i</sub>] == 0</code>.</p>

<p>Return <em>the order of the largest <strong>axis-aligned</strong> plus sign of </em>1<em>&#39;s contained in </em><code>grid</code>. If there is none, return <code>0</code>.</p>

<p>An <strong>axis-aligned plus sign</strong> of <code>1</code>&#39;s of order <code>k</code> has some center <code>grid[r][c] == 1</code> along with four arms of length <code>k - 1</code> going up, down, left, and right, and made of <code>1</code>&#39;s. Note that there could be <code>0</code>&#39;s or <code>1</code>&#39;s beyond the arms of the plus sign, only the relevant area of the plus sign is checked for <code>1</code>&#39;s.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/06/13/plus1-grid.jpg" style="width: 404px; height: 405px;" />
<pre>
<strong>Input:</strong> n = 5, mines = [[4,2]]
<strong>Output:</strong> 2
<strong>Explanation:</strong> In the above grid, the largest plus sign can only be of order 2. One of them is shown.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/06/13/plus2-grid.jpg" style="width: 84px; height: 85px;" />
<pre>
<strong>Input:</strong> n = 1, mines = [[0,0]]
<strong>Output:</strong> 0
<strong>Explanation:</strong> There is no plus sign, so return 0.
</pre>

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

<ul>
	<li><code>1 &lt;= n &lt;= 500</code></li>
	<li><code>1 &lt;= mines.length &lt;= 5000</code></li>
	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt; n</code></li>
	<li>All the pairs <code>(x<sub>i</sub>, y<sub>i</sub>)</code> are <strong>unique</strong>.</li>
</ul>

class Solution {
public:
    int orderOfLargestPlusSign(int n, vector<vector<int>>& mines)
    {
        int dirs[4][2] =   { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } };
        int c, d, g, i, j, k, l, m, r, * *w;

        r = 0;
        w = new int *[n];
        for (i = 0; i < n; i++) {
            w[i] = new int[n];
            std::fill(&w[i][0], &w[i][n], 1);
        }
        for (i = 0; i < mines.size(); i++)
            w[mines[i][0]][mines[i][1]] = 0;
        m = n / 2;
        c = 1;
        for (l = 0; l <= n && r <= m - (l / 2); l += 2) {
            i = m - (l / 2);
            j = m - (l / 2);
            for (g = 0; g < c; g++) {
                k = 0;
                do {
                    if (i >= 0 && i < n && j >= 0 && j < n &&
                        w[i][j] == 1) {
                        d = 1;
                        while (i - d >= 0 && i + d < n && j - d >= 0 &&
                               j + d < n && w[i - d][j] == 1 &&
                               w[i][j + d] == 1 && w[i + d][j] == 1 &&
                               w[i][j - d] == 1)
                            d++;
                        if (r < d)
                            r = d;
                    }
                    i += dirs[g][0];
                    j += dirs[g][1];
                } while (++k < l);
            }
            c = 4;
        }
        for (i = 0; i < n; i++)
            delete[] w[i];
        delete[] w;

        return r;
    }
};
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