60 lines
1.7 KiB
Kotlin
60 lines
1.7 KiB
Kotlin
/**
|
|
* File: graph_dfs.kt
|
|
* Created Time: 2024-01-25
|
|
* Author: curtishd (1023632660@qq.com)
|
|
*/
|
|
|
|
package chapter_graph
|
|
|
|
import utils.Vertex
|
|
|
|
/* Depth-first traversal helper function */
|
|
fun dfs(
|
|
graph: GraphAdjList,
|
|
visited: MutableSet<Vertex?>,
|
|
res: MutableList<Vertex?>,
|
|
vet: Vertex?
|
|
) {
|
|
res.add(vet) // Record visited vertex
|
|
visited.add(vet) // Mark the vertex as visited
|
|
// Traverse all adjacent vertices of that vertex
|
|
for (adjVet in graph.adjList[vet]!!) {
|
|
if (visited.contains(adjVet))
|
|
continue // Skip already visited vertices
|
|
// Recursively visit adjacent vertices
|
|
dfs(graph, visited, res, adjVet)
|
|
}
|
|
}
|
|
|
|
/* Depth-first traversal */
|
|
// Use adjacency list to represent the graph, to obtain all adjacent vertices of a specified vertex
|
|
fun graphDFS(graph: GraphAdjList, startVet: Vertex?): MutableList<Vertex?> {
|
|
// Vertex traversal sequence
|
|
val res = mutableListOf<Vertex?>()
|
|
// Hash set, used to record visited vertices
|
|
val visited = HashSet<Vertex?>()
|
|
dfs(graph, visited, res, startVet)
|
|
return res
|
|
}
|
|
|
|
/* Driver Code */
|
|
fun main() {
|
|
/* Initialize undirected graph */
|
|
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("\nAfter initialization, the graph is")
|
|
graph.print()
|
|
|
|
/* Depth-first traversal */
|
|
val res = graphDFS(graph, v[0])
|
|
println("\nDepth-first traversal (DFS) vertex sequence is")
|
|
println(Vertex.vetsToVals(res))
|
|
} |