标签：class more wrap inf output nat ble one nta
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.
Nodes in a connected component should sort by label in ascending order. Different connected components can be in any order.
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
\ | |
\ | |
\ | |
\ | |
4 5
Example 2:
Input: {1,2#2,1} Output: [[1,2]] Explanation: 1--2
思路：无向图连通块, 可以使用BFS或者并查集union find求解 .
/**
* Definition for Undirected graph.
* class UndirectedGraphNode {
* int label;
* ArrayList<UndirectedGraphNode> neighbors;
* UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
* };
*/
public
class Solution {
class UnionFind {
HashMap<Integer, Integer> father = new HashMap<Integer, Integer>();
UnionFind(HashSet<Integer> hashSet)
{
for (Integer now : hashSet) {
father.put(now, now);
}
}
int find(int x)
{
int parent = father.get(x);
while (parent != father.get(parent)) {
parent = father.get(parent);
}
return parent;
}
int compressed_find(int x)
{
int parent = father.get(x);
while (parent != father.get(parent)) {
parent = father.get(parent);
}
int next;
while (x != father.get(x)) {
next = father.get(x);
father.put(x, parent);
x = next;
}
return parent;
}
void union(int x, int y)
{
int fa_x = find(x);
int fa_y = find(y);
if (fa_x != fa_y)
father.put(fa_x, fa_y);
}
}
List<List<Integer> > print(HashSet<Integer> hashSet, UnionFind uf, int n) {
List<List<Integer> > ans = new ArrayList<List<Integer> >();
HashMap<Integer, List<Integer> > hashMap = new HashMap<Integer, List<Integer> >();
for (int i : hashSet) {
int fa = uf.find(i);
if (!hashMap.containsKey(fa)) {
hashMap.put(fa, new ArrayList<Integer>());
}
List<Integer> now = hashMap.get(fa);
now.add(i);
hashMap.put(fa, now);
}
for (List<Integer> now : hashMap.values()) {
Collections.sort(now);
ans.add(now);
}
return ans;
}
public
List<List<Integer> > connectedSet(List<UndirectedGraphNode> nodes)
{
// Write your code here
HashSet<Integer> hashSet = new HashSet<Integer>();
for (UndirectedGraphNode now : nodes) {
hashSet.add(now.label);
for (UndirectedGraphNode neighbour : now.neighbors) {
hashSet.add(neighbour.label);
}
}
UnionFind uf = new UnionFind(hashSet);
for (UndirectedGraphNode now : nodes) {
for (UndirectedGraphNode neighbour : now.neighbors) {
int fnow = uf.find(now.label);
int fneighbour = uf.find(neighbour.label);
if (fnow != fneighbour) {
uf.union(now.label, neighbour.label);
}
}
}
return print(hashSet, uf, nodes.size());
}
}
Connected Component in Undirected Graph
标签：class more wrap inf output nat ble one nta
原文地址：https://www.cnblogs.com/FLAGyuri/p/12078607.html
