mirror of
https://github.com/krahets/hello-algo.git
synced 2025-10-31 18:37:48 +08:00
67 lines
1.8 KiB
Dart
67 lines
1.8 KiB
Dart
/**
|
||
* File: graph_bfs.dart
|
||
* Created Time: 2023-05-15
|
||
* Author: liuyuxin (gvenusleo@gmail.com)
|
||
*/
|
||
|
||
import 'dart:collection';
|
||
|
||
import '../utils/vertex.dart';
|
||
import 'graph_adjacency_list.dart';
|
||
|
||
/* 广度优先遍历 */
|
||
List<Vertex> graphBFS(GraphAdjList graph, Vertex startVet) {
|
||
// 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
|
||
// 顶点遍历序列
|
||
List<Vertex> res = [];
|
||
// 哈希集合，用于记录已被访问过的顶点
|
||
Set<Vertex> visited = {};
|
||
visited.add(startVet);
|
||
// 队列用于实现 BFS
|
||
Queue<Vertex> que = Queue();
|
||
que.add(startVet);
|
||
// 以顶点 vet 为起点，循环直至访问完所有顶点
|
||
while (que.isNotEmpty) {
|
||
Vertex vet = que.removeFirst(); // 队首顶点出队
|
||
res.add(vet); // 记录访问顶点
|
||
// 遍历该顶点的所有邻接顶点
|
||
for (Vertex adjVet in graph.adjList[vet]!) {
|
||
if (visited.contains(adjVet)) {
|
||
continue; // 跳过已被访问的顶点
|
||
}
|
||
que.add(adjVet); // 只入队未访问的顶点
|
||
visited.add(adjVet); // 标记该顶点已被访问
|
||
}
|
||
}
|
||
// 返回顶点遍历序列
|
||
return res;
|
||
}
|
||
|
||
/* Dirver Code */
|
||
void main() {
|
||
/* 初始化无向图 */
|
||
List<Vertex> v = Vertex.valsToVets([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
|
||
List<List<Vertex>> 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]],
|
||
];
|
||
GraphAdjList graph = GraphAdjList(edges);
|
||
print("\n初始化后，图为");
|
||
graph.printAdjList();
|
||
|
||
/* 广度优先遍历 */
|
||
List<Vertex> res = graphBFS(graph, v[0]);
|
||
print("\n广度优先遍历（BFS）顶点序列为");
|
||
print(Vertex.vetsToVals(res));
|
||
}
|