431. Connected Component in Undirected Graph
中文English
Find connected component in undirected graph.
Each node in the graph contains a label and a list of its neighbors.
(A connected component of an undirected graph is a subgraph in which any two vertices are connected to each other by paths, and which is connected to no additional vertices in the supergraph.)
You need return a list of label set.
Example
Example 1:
Input: {1,2,4#2,1,4#3,5#4,1,2#5,3}
Output: [[1,2,4],[3,5]]
Explanation:
1------2 3
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4 5
Example 2:
Input: {1,2#2,1}
Output: [[1,2]]
Explanation:
1--2
Clarification
Notice
Nodes in a connected component should sort by label in ascending order. Different connected components can be in any order.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 | /** * Definition for Undirected graph. * class UndirectedGraphNode { * int label; * ArrayList<UndirectedGraphNode> neighbors; * UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); } * }; */public class Solution { /* * @param nodes: a array of Undirected graph node * @return: a connected set of a Undirected graph */ public List<List<Integer>> connectedSet(List<UndirectedGraphNode> nodes) { // write your code here List<List<Integer>> ans = new ArrayList<>(); if (nodes == null || nodes.size() == 0) { return ans; } Map<UndirectedGraphNode, List<UndirectedGraphNode>> adjList = new HashMap<>(); for (UndirectedGraphNode node : nodes) { adjList.put(node, node.neighbors); } Set<UndirectedGraphNode> visited = new HashSet<>(); for (UndirectedGraphNode node : nodes) { if (!visited.contains(node)) { List<Integer> cc = bfs(adjList, node, visited); ans.add(cc); } } return ans; } private List<Integer> bfs(Map<UndirectedGraphNode, List<UndirectedGraphNode>> adjList, UndirectedGraphNode node, Set<UndirectedGraphNode> visited) { List<Integer> ans = new ArrayList<>(); Queue<UndirectedGraphNode> queue = new LinkedList<>(); queue.offer(node); visited.add(node); while (!queue.isEmpty()) { UndirectedGraphNode v = queue.poll(); ans.add(v.label); for (UndirectedGraphNode neighbor : adjList.get(v)) { if (visited.contains(neighbor)) { continue; } queue.offer(neighbor); visited.add(neighbor); } } Collections.sort(ans); return ans; }} |
