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* 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
65 lines
1.9 KiB
Kotlin
65 lines
1.9 KiB
Kotlin
/**
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* File: graph_bfs.kt
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* Created Time: 2024-01-25
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* Author: curtishd (1023632660@qq.com)
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*/
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package chapter_graph
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import utils.Vertex
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import java.util.*
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/* 廣度優先走訪 */
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// 使用鄰接表來表示圖，以便獲取指定頂點的所有鄰接頂點
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fun graphBFS(graph: GraphAdjList, startVet: Vertex): MutableList<Vertex?> {
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// 頂點走訪序列
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val res = mutableListOf<Vertex?>()
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// 雜湊集合，用於記錄已被訪問過的頂點
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val visited = HashSet<Vertex>()
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visited.add(startVet)
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// 佇列用於實現 BFS
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val que = LinkedList<Vertex>()
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que.offer(startVet)
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// 以頂點 vet 為起點，迴圈直至訪問完所有頂點
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while (!que.isEmpty()) {
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val vet = que.poll() // 佇列首頂點出隊
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res.add(vet) // 記錄訪問頂點
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// 走訪該頂點的所有鄰接頂點
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for (adjVet in graph.adjList[vet]!!) {
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if (visited.contains(adjVet))
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continue // 跳過已被訪問的頂點
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que.offer(adjVet) // 只入列未訪問的頂點
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visited.add(adjVet) // 標記該頂點已被訪問
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}
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}
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// 返回頂點走訪序列
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return res
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}
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/* Driver Code */
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fun main() {
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/* 初始化無向圖 */
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val v = Vertex.valsToVets(intArrayOf(0, 1, 2, 3, 4, 5, 6, 7, 8, 9))
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val edges = arrayOf(
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arrayOf(v[0], v[1]),
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arrayOf(v[0], v[3]),
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arrayOf(v[1], v[2]),
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arrayOf(v[1], v[4]),
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arrayOf(v[2], v[5]),
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arrayOf(v[3], v[4]),
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arrayOf(v[3], v[6]),
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arrayOf(v[4], v[5]),
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arrayOf(v[4], v[7]),
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arrayOf(v[5], v[8]),
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arrayOf(v[6], v[7]),
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arrayOf(v[7], v[8])
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)
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val graph = GraphAdjList(edges)
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println("\n初始化後，圖為")
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graph.print()
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/* 廣度優先走訪 */
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val res = graphBFS(graph, v[0]!!)
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println("\n廣度優先走訪（BFS）頂點序列為")
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println(Vertex.vetsToVals(res))
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} |