hello-algo/codes/kotlin/chapter_graph/graph_dfs.kt

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/**
* File: graph_dfs.kt
* Created Time: 2024-01-25
* Author: curtishd (1023632660@qq.com)
*/
package chapter_graph
import utils.Vertex
/* 深度优先遍历辅助函数 */
fun dfs(
graph: GraphAdjList,
visited: MutableSet<Vertex?>,
res: MutableList<Vertex?>,
vet: Vertex?
) {
res.add(vet) // 记录访问顶点
visited.add(vet) // 标记该顶点已被访问
// 遍历该顶点的所有邻接顶点
for (adjVet in graph.adjList[vet]!!) {
if (visited.contains(adjVet))
continue // 跳过已被访问的顶点
// 递归访问邻接顶点
dfs(graph, visited, res, adjVet)
}
}
/* 深度优先遍历 */
// 使用邻接表来表示图,以便获取指定顶点的所有邻接顶点
fun graphDFS(graph: GraphAdjList, startVet: Vertex?): MutableList<Vertex?> {
// 顶点遍历序列
val res = mutableListOf<Vertex?>()
// 哈希集合,用于记录已被访问过的顶点
val visited = HashSet<Vertex?>()
dfs(graph, visited, res, startVet)
return res
}
/* Driver Code */
fun main() {
/* 初始化无向图 */
val v = Vertex.valsToVets(intArrayOf(0, 1, 2, 3, 4, 5, 6))
val edges = arrayOf(
arrayOf(v[0], v[1]),
arrayOf(v[0], v[3]),
arrayOf(v[1], v[2]),
arrayOf(v[2], v[5]),
arrayOf(v[4], v[5]),
arrayOf(v[5], v[6])
)
val graph = GraphAdjList(edges)
println("\n初始化后,图为")
graph.print()
/* 深度优先遍历 */
val res = graphDFS(graph, v[0])
println("\n深度优先遍历DFS顶点序列为")
println(Vertex.vetsToVals(res))
}