LeetCode Solutions : N-Queens II

N皇后问题的总解数

最新推荐文章于 2019-04-09 23:31:09 发布

lviiii

最新推荐文章于 2019-04-09 23:31:09 发布

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本文探讨了N皇后问题的解决策略，并提供了Java实现，通过递归深度优先搜索算法计算不同规模棋盘上的所有独特解决方案数量。

Follow up for N-Queens problem.

Now, instead outputting board configurations, return the total number of distinct solutions.

Java Solutions( Refer to blog http://blog.youkuaiyun.com/mbh_1991/article/details/23869459 and http://blog.youkuaiyun.com/u011095253/article/details/9158473 ):

public class Solution {
	int count;
    public int totalNQueens(int n) {
        count=0;
		int[] location=new int[n];
		dfs(location,0,n);
		return count;
    }
	private void dfs(int[] location,int cur,int n){
		if(cur==n)
			count++;
		else{
			for(int i=0;i<n;i++){
				location[cur]=i;
				if(isValid(location,cur))
					dfs(location,cur+1,n);
			}
		}
	}
	private boolean isValid(int[] location,int cur){
		for(int i=0;i<cur;i++){
			if(location[i]==location[cur]||Math.abs(location[i]-location[cur])==cur-i)
				return false;
		}
		return true;
	}
}