N-Queens Problem

 

N-Queens Problem:

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other, which means no two queens share the same row, column, or diagonal. 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.

This problem can be solved recursively: for every free grid in a row, resursively check possible solutions in the row below, until (1) there is no free grid in the next row(failure) or (2) there is no row below(current row is the last row, sucess).

- See more at:http://bo-yang.github.io/2014/06/27/nqueens/#sthash.0lhIffcj.dpuf

 http://bo-yang.github.io/2014/06/27/nqueens