04b0fb7455
* refactor: extract Vertex and use Array<Vertex> * docs: add chapter to Package.swift * Update graph_adjacency_list.swift --------- Co-authored-by: Yudong Jin <krahets@163.com>
122 lines
3.3 KiB
Swift
122 lines
3.3 KiB
Swift
/**
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* File: graph_adjacency_list.swift
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* Created Time: 2023-02-01
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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import utils
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/* 基于邻接表实现的无向图类 */
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class GraphAdjList {
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// 邻接表，使用哈希表来代替链表，以提升删除边、删除顶点的效率
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// 请注意，adjList 中的元素是 Vertex 对象
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private var adjList: [Vertex: [Vertex]]
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/* 构造方法 */
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init(edges: [[Vertex]]) {
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adjList = [:]
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// 添加所有顶点和边
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for edge in edges {
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addVertex(vet: edge[0])
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addVertex(vet: edge[1])
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addEdge(vet1: edge[0], vet2: edge[1])
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}
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}
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/* 获取顶点数量 */
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func size() -> Int {
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adjList.count
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}
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/* 添加边 */
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func addEdge(vet1: Vertex, vet2: Vertex) {
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if adjList[vet1] == nil || adjList[vet2] == nil || vet1 == vet2 {
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fatalError("参数错误")
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}
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// 添加边 vet1 - vet2
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adjList[vet1]?.append(vet2)
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adjList[vet2]?.append(vet1)
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}
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/* 删除边 */
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func removeEdge(vet1: Vertex, vet2: Vertex) {
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if adjList[vet1] == nil || adjList[vet2] == nil || vet1 == vet2 {
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fatalError("参数错误")
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}
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// 删除边 vet1 - vet2
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adjList[vet1]?.removeAll(where: { $0 == vet2 })
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adjList[vet2]?.removeAll(where: { $0 == vet1 })
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}
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/* 添加顶点 */
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func addVertex(vet: Vertex) {
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if adjList[vet] != nil {
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return
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}
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// 在邻接表中添加一个新链表
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adjList[vet] = []
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}
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/* 删除顶点 */
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func removeVertex(vet: Vertex) {
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if adjList[vet] == nil {
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fatalError("参数错误")
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}
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// 在邻接表中删除顶点 vet 对应的链表
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adjList.removeValue(forKey: vet)
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// 遍历其它顶点的链表，删除所有包含 vet 的边
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for key in adjList.keys {
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adjList[key]?.removeAll(where: { $0 == vet })
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}
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}
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/* 打印邻接表 */
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func print() {
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Swift.print("邻接表 =")
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for entry in adjList {
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var tmp: [Int] = []
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for vertex in entry.value {
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tmp.append(vertex.val)
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}
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Swift.print("\(entry.key.val): \(tmp),")
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}
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}
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}
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@main
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enum GraphAdjacencyList {
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/* Driver Code */
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static func main() {
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/* 初始化无向图 */
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let v = Vertex.valsToVets([1, 3, 2, 5, 4])
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let edges = [[v[0], v[1]], [v[0], v[3]], [v[1], v[2]], [v[2], v[3]], [v[2], v[4]], [v[3], v[4]]]
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let graph = GraphAdjList(edges: edges)
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print("\n初始化后，图为")
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graph.print()
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/* 添加边 */
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// 顶点 1, 2 即 v[0], v[2]
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graph.addEdge(vet1: v[0], vet2: v[2])
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print("\n添加边 1-2 后，图为")
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graph.print()
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/* 删除边 */
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// 顶点 1, 3 即 v[0], v[1]
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graph.removeEdge(vet1: v[0], vet2: v[1])
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print("\n删除边 1-3 后，图为")
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graph.print()
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/* 添加顶点 */
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let v5 = Vertex(val: 6)
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graph.addVertex(vet: v5)
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print("\n添加顶点 6 后，图为")
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graph.print()
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/* 删除顶点 */
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// 顶点 3 即 v[1]
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graph.removeVertex(vet: v[1])
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print("\n删除顶点 3 后，图为")
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graph.print()
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}
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}
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