<p>The <strong>n-queens</strong> puzzle is the problem of placing <code>n</code> queens on an <code>n x n</code> chessboard such that no two queens attack each other.</p>

<p>Given an integer <code>n</code>, return <em>all distinct solutions to the <strong>n-queens puzzle</strong></em>. You may return the answer in <strong>any order</strong>.</p>

<p>Each solution contains a distinct board configuration of the n-queens&#39; placement, where <code>&#39;Q&#39;</code> and <code>&#39;.&#39;</code> both indicate a queen and an empty space, respectively.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/queens.jpg" style="width: 600px; height: 268px;" />
<pre>
<strong>Input:</strong> n = 4
<strong>Output:</strong> [[&quot;.Q..&quot;,&quot;...Q&quot;,&quot;Q...&quot;,&quot;..Q.&quot;],[&quot;..Q.&quot;,&quot;Q...&quot;,&quot;...Q&quot;,&quot;.Q..&quot;]]
<strong>Explanation:</strong> There exist two distinct solutions to the 4-queens puzzle as shown above
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> n = 1
<strong>Output:</strong> [[&quot;Q&quot;]]
</pre>

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

<ul>
	<li><code>1 &lt;= n &lt;= 9</code></li>
</ul>

class Solution {
public:
    vector<string> markRowsColumnsAndDiaginal(vector<string> v, int i, int j) {
        vector<string> board = v;
        int n = v.size();
        for(int k = 0; k < n; k++) {
            board[k][j] = '.';
            board[i][k] = '.';
        }
        int k = i, l = j;
        while(k < n && l < n) {
          board[k][l] = '.';
          k++; l++;
        }
        k = i;
        l = j;
        while(k < n && l >= 0) {
          board[k][l] = '.';
          k++; l--;
        }
        board[i][j] = 'Q';

        return board;
        
    }
    void solveNQueensRecur(vector<vector<string>> &res, vector<string> curr, int rowIndex) {
        if(rowIndex >= curr.size()) {
          res.push_back(curr);
          return;
        }
        for(int j=0; j<curr[rowIndex].length(); j++) {
           if(curr[rowIndex][j] == 'Q') {
              vector<string> temp = markRowsColumnsAndDiaginal(curr, rowIndex, j);
              solveNQueensRecur(res, temp, rowIndex + 1);
           }
        }
    }
    vector<vector<string>> solveNQueens(int n) {
        vector<vector<string>> res;
        string s = "";
        for(int i=0; i<n; i++) {
          s += "Q";
        }
        vector<string> curr(n, s);
        solveNQueensRecur(res, curr, 0);
        return res;
    }
};
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