Queens That Can Attack the King
<p>On a <strong>0-indexed</strong> <code>8 x 8</code> chessboard, there can be multiple black queens and one white king.</p>

<p>You are given a 2D integer array <code>queens</code> where <code>queens[i] = [xQueen<sub>i</sub>, yQueen<sub>i</sub>]</code> represents the position of the <code>i<sup>th</sup></code> black queen on the chessboard. You are also given an integer array <code>king</code> of length <code>2</code> where <code>king = [xKing, yKing]</code> represents the position of the white king.</p>

<p>Return <em>the coordinates of the black queens that can directly attack the king</em>. You may return the answer in <strong>any order</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1200-1299/1222.Queens%20That%20Can%20Attack%20the%20King/images/chess1.jpg" style="width: 400px; height: 400px;" />
<pre>
<strong>Input:</strong> queens = [[0,1],[1,0],[4,0],[0,4],[3,3],[2,4]], king = [0,0]
<strong>Output:</strong> [[0,1],[1,0],[3,3]]
<strong>Explanation:</strong> The diagram above shows the three queens that can directly attack the king and the three queens that cannot attack the king (i.e., marked with red dashes).
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1200-1299/1222.Queens%20That%20Can%20Attack%20the%20King/images/chess2.jpg" style="width: 400px; height: 400px;" />
<pre>
<strong>Input:</strong> queens = [[0,0],[1,1],[2,2],[3,4],[3,5],[4,4],[4,5]], king = [3,3]
<strong>Output:</strong> [[2,2],[3,4],[4,4]]
<strong>Explanation:</strong> The diagram above shows the three queens that can directly attack the king and the three queens that cannot attack the king (i.e., marked with red dashes).
</pre>

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

<ul>
	<li><code>1 &lt;= queens.length &lt; 64</code></li>
	<li><code>queens[i].length == king.length == 2</code></li>
	<li><code>0 &lt;= xQueen<sub>i</sub>, yQueen<sub>i</sub>, xKing, yKing &lt; 8</code></li>
	<li>All the given positions are <strong>unique</strong>.</li>
</ul>
Array; Matrix; Simulation
class Solution {
public:
    vector<vector<int>> queensAttacktheKing(vector<vector<int>>& queens, vector<int>& king) {
        int n = 8;
        bool s[8][8]{};
        for (auto& q : queens) {
            s[q[0]][q[1]] = true;
        }
        vector<vector<int>> ans;
        for (int a = -1; a <= 1; ++a) {
            for (int b = -1; b <= 1; ++b) {
                if (a || b) {
                    int x = king[0] + a, y = king[1] + b;
                    while (x >= 0 && x < n && y >= 0 && y < n) {
                        if (s[x][y]) {
                            ans.push_back({x, y});
                            break;
                        }
                        x += a;
                        y += b;
                    }
                }
            }
        }
        return ans;
    }
};