leetcode 52. N-Queens II

一 题目

  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 the number of distinct solutions to the n-queens puzzle.

Example:

Input: 4
Output: 2
Explanation: There are two distinct solutions to the 4-queens puzzle as shown below.
[
 [".Q..",  // Solution 1
  "...Q",
  "Q...",
  "..Q."],

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

二  分析

hard 级别，还是跟上个题目leetcode 51. N-Queens 一样的，但是这个更简单些，只输出个数，不求具体的位置。

稍微改一下上个题的方式，返回结果改为全局的计数变量。

 static int res ;
	 public static int totalNQueens(int n) {
	        res =0;
	        int[] queens = new int[n];
			 //初始化-1
			 for(int i=0;i

 

Runtime: 2 ms, faster than 55.53% of Java online submissions for N-Queens II.

Memory Usage: 32.7 MB, less than 13.04% of Java online submissions for N-Queens II.