310. Minimum Height Trees queue:  degree为1的顶点 degree[ i ] : 和 i 顶点关联的边数. 先添加整个图,然后BFS删除每一层degree为1的节点. class Solution { public List<Integer> findMinHeightTrees(int n, int[][] edges) { List<Integer> result = new ArrayList<>(); if(n == 1){…

2014-11-30 Created By BaoXinjian…

[题目链接] http://uoj.ac/problem/310 [题目大意] 给出一个数集,A从中选择一些数,B从中选择一些数,不能同时不选 要求两者选择的数异或和为0,问方案数 [题解] 题目等价于选取一个非空且xor为0的集合并将其拆分为两个子集的方案数 用dp表示xor为j的方案数,易得dp方程dp[i][j]=dp[i-1][j]+2*dp[i-1][j^a[i]] 该式等价于dp数组与只有两个元素有值的g[0]=1,g[a[i]]=2的数组做卷积运算 对g数组进行反演可以发现每次卷积…

1.UNION的作用  UNION 指令的目的是将两个 SQL 语句的结果合并起来.从这个角度来看, UNION 跟 JOIN 有些许类似,因为这两个指令都可以由多个表格中撷取资料. UNION 的一个限制是两个 SQL 语句所产生的栏位需要是同样的资料种类.另外,当我们用 UNION这个指令时,我们只会看到不同的资料值 (类似 SELECT DISTINCT). union只是将两个结果联结起来一起显示,并不是联结两个表………… UNION 的语法如下: [SQL 语句 1]  假设我们有以下…

原题链接在这里:https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/ 题目: Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected com…

Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to check whether these edges make up a valid tree. For example: Given n = 5 and edges = [[0, 1], [0, 2], [0, 3], [1, 4]], return tru…

［抄题］: Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph. Example 1: Input: n = 5 and edges = [[0, 1], [1, 2], [3, 4]…

原题链接在这里:https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/ 题目: Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected com…

Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph. Example 1: Input: n = 5 and edges = [[0, 1], [1, 2], [3, 4]] 0 3…

Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph. Example 1: | | --- Given n = 5 and edges = [[0, 1], [1, 2], [3, 4…