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.."] ]
Solution:
大神的做法：
http://blog.csdn.net/xift810/article/details/22187633
1 public class Solution { 2 public List<String[]> solveNQueens(int n) { 3 List<String[]> result = new ArrayList<String[]>(); 4 if (n == 0) 5 return result; 6 int[] rCol = new int[n]; 7 queens(result, rCol, 0, n); 8 return result; 9 } 10 11 private void queens(List<String[]> result, int[] rCol, int row, int n) { 12 // TODO Auto-generated method stub 13 if (row == n) { 14 printQueens(result, rCol, n); 15 return; 16 } 17 for (int col = 0; col < n; ++col) { 18 rCol[row] = col; 19 if (check(rCol, row)) { 20 queens(result, rCol, row + 1, n); 21 } 22 } 23 } 24 25 private boolean check(int[] rCol, int row) { 26 // TODO Auto-generated method stub 27 for (int i = 0; i < row; ++i) { 28 if (rCol[i] == rCol[row]) 29 return false; 30 if (Math.abs(row - i) == Math.abs(rCol[row] - rCol[i])) { 31 return false; 32 } 33 } 34 return true; 35 } 36 37 private void printQueens(List<String[]> result, int[] rCol, int n) { 38 // TODO Auto-generated method stub 39 String[] s = new String[n]; 40 for (int i = 0; i < n; ++i) { 41 String temp = ""; 42 for (int j = 0; j < n; ++j) { 43 if(rCol[i]==j){ 44 temp+="Q"; 45 }else{ 46 temp+="."; 47 } 48 } 49 s[i]=temp; 50 } 51 result.add(s); 52 } 53 }
原文：http://www.cnblogs.com/Phoebe815/p/4032469.html