LeetCode-N-Queens

The n-queens puzzle is the problem of placing n queens on an n�n chessboard such that no two queens attack each other.

Given an integer n, return all distinct solutions to the n-queens puzzle.

Each solution contains a distinct board configuration of the n-queens' placement, where 'Q' and '.' both indicate a queen and an empty space respectively.

For example,
There exist two distinct solutions to the 4-queens puzzle:

[
 [".Q..",  // Solution 1
  "...Q",
  "Q...",
  "..Q."],

 ["..Q.",  // Solution 2
  "Q...",
  "...Q",
  ".Q.."]
]

class Solution {
public:
    int check(int* X,int k){
		for(int i=0;i<k;i++){
			if(X[i]==X[k]||abs(X[i]-X[k])==abs(i-k))return -1;
		}
		return 0;
	}
	vector<vector<string> > solveNQueens(int n) {
		// Start typing your C/C++ solution below
		// DO NOT write int main() function
		vector<vector<string> > ret;
		int* X=new int[n+1];
		X[0]=-1;
		int j=0;
		while(j>=0)
		{
			X[j]++;
			if(X[j]==n)
			{
				j--;
				continue;
			}
			if(check(X,j)<0)
			{
					continue;
			}
			else
			{
				j++;
				if(j==n){
					vector<string> result;
					for(int i=0;i<n;i++){
						string s;
						s.resize(n,'.');
						s[X[i]]='Q';
						result.push_back(s);
					}
					ret.push_back(result);
					j--;
				}
				else
				{
					X[j]=-1;
				}
			}
		}
		delete X;
		return ret;
	}
};