mirror of
https://github.com/krahets/hello-algo.git
synced 2024-12-26 08:26:29 +08:00
870e3e5cb2
* Sync zh and zh-hant versions * Update en/README.md * Add a Q&A for chapter of introduction * Update the callout headers * Sync zh ang zh-hant versions * Bug fixes
56 lines
1.8 KiB
Swift
56 lines
1.8 KiB
Swift
/**
|
||
* File: graph_bfs.swift
|
||
* Created Time: 2023-02-21
|
||
* Author: nuomi1 (nuomi1@qq.com)
|
||
*/
|
||
|
||
import graph_adjacency_list_target
|
||
import utils
|
||
|
||
/* 廣度優先走訪 */
|
||
// 使用鄰接表來表示圖，以便獲取指定頂點的所有鄰接頂點
|
||
func graphBFS(graph: GraphAdjList, startVet: Vertex) -> [Vertex] {
|
||
// 頂點走訪序列
|
||
var res: [Vertex] = []
|
||
// 雜湊集合，用於記錄已被訪問過的頂點
|
||
var visited: Set<Vertex> = [startVet]
|
||
// 佇列用於實現 BFS
|
||
var que: [Vertex] = [startVet]
|
||
// 以頂點 vet 為起點，迴圈直至訪問完所有頂點
|
||
while !que.isEmpty {
|
||
let vet = que.removeFirst() // 佇列首頂點出隊
|
||
res.append(vet) // 記錄訪問頂點
|
||
// 走訪該頂點的所有鄰接頂點
|
||
for adjVet in graph.adjList[vet] ?? [] {
|
||
if visited.contains(adjVet) {
|
||
continue // 跳過已被訪問的頂點
|
||
}
|
||
que.append(adjVet) // 只入列未訪問的頂點
|
||
visited.insert(adjVet) // 標記該頂點已被訪問
|
||
}
|
||
}
|
||
// 返回頂點走訪序列
|
||
return res
|
||
}
|
||
|
||
@main
|
||
enum GraphBFS {
|
||
/* Driver Code */
|
||
static func main() {
|
||
/* 初始化無向圖 */
|
||
let v = Vertex.valsToVets(vals: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
|
||
let edges = [
|
||
[v[0], v[1]], [v[0], v[3]], [v[1], v[2]], [v[1], v[4]],
|
||
[v[2], v[5]], [v[3], v[4]], [v[3], v[6]], [v[4], v[5]],
|
||
[v[4], v[7]], [v[5], v[8]], [v[6], v[7]], [v[7], v[8]],
|
||
]
|
||
let graph = GraphAdjList(edges: edges)
|
||
print("\n初始化後，圖為")
|
||
graph.print()
|
||
|
||
/* 廣度優先走訪 */
|
||
let res = graphBFS(graph: graph, startVet: v[0])
|
||
print("\n廣度優先走訪（BFS）頂點序列為")
|
||
print(Vertex.vetsToVals(vets: res))
|
||
}
|
||
}
|