<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:
    map<int,int> straightline;
    map<int,int> diagonallyleft;
    map<int,int> diagonallyright;
    vector<vector<string>> solveNQueens(int n) {
        vector<vector<string>> output;
        vector<int> path;
        solve(n,0,output,path);
        return output;        
    }

    void solve(int& n,int row,vector<vector<string>>& output,vector<int> path){
        if(row==n){
            make_ans(output,path,n);
            return;
        }
        for(int i=0;i<n;i++){
            if(isSafe(row,i,n)){
                path.push_back(i);
                straightline[i]++;
                diagonallyright[row+i]++;
                diagonallyleft[row-i]++;
                solve(n,row+1,output,path);
                straightline[i]--;
                diagonallyright[row+i]--;
                diagonallyleft[row-i]--;
                path.pop_back();
            }
        }
        return;
    }
bool isSafe(int row,int col,int n){
        if (straightline[col] || diagonallyright[row + col] || diagonallyleft[row-col]) {
            return false;
        }
        return true;
    }
    

    void make_ans(vector<vector<string>>& output,vector<int> path,int n){
        vector<string> ans;
        for(auto i:path){
            string temp(n,'.');
            temp[i]='Q';
            ans.push_back(temp);
        }
        output.push_back(ans);

    }
};
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