feat: add Swift codes for graph_traversal article (#378)

* feat: add Swift codes for graph_traversal article

* refactor: rename parameters

* Update graph_dfs.swift

---------

Co-authored-by: Yudong Jin <krahets@163.com>

codes/swift/chapter_graph/graph_adjacency_list.swift

@@ -7,13 +7,13 @@
 import utils
 
 /* 基于邻接表实现的无向图类 */
-class GraphAdjList {
+public class GraphAdjList {
     // 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
     // 请注意，adjList 中的元素是 Vertex 对象
-    private var adjList: [Vertex: [Vertex]]
+    public private(set) var adjList: [Vertex: [Vertex]]
 
     /* 构造方法 */
-    init(edges: [[Vertex]]) {
+    public init(edges: [[Vertex]]) {
         adjList = [:]
         // 添加所有顶点和边
         for edge in edges {
@@ -24,12 +24,12 @@ class GraphAdjList {
     }
 
     /* 获取顶点数量 */
-    func size() -> Int {
+    public func size() -> Int {
         adjList.count
     }
 
     /* 添加边 */
-    func addEdge(vet1: Vertex, vet2: Vertex) {
+    public func addEdge(vet1: Vertex, vet2: Vertex) {
         if adjList[vet1] == nil || adjList[vet2] == nil || vet1 == vet2 {
             fatalError("参数错误")
         }
@@ -39,7 +39,7 @@ class GraphAdjList {
     }
 
     /* 删除边 */
-    func removeEdge(vet1: Vertex, vet2: Vertex) {
+    public func removeEdge(vet1: Vertex, vet2: Vertex) {
         if adjList[vet1] == nil || adjList[vet2] == nil || vet1 == vet2 {
             fatalError("参数错误")
         }
@@ -49,7 +49,7 @@ class GraphAdjList {
     }
 
     /* 添加顶点 */
-    func addVertex(vet: Vertex) {
+    public func addVertex(vet: Vertex) {
         if adjList[vet] != nil {
             return
         }
@@ -58,7 +58,7 @@ class GraphAdjList {
     }
 
     /* 删除顶点 */
-    func removeVertex(vet: Vertex) {
+    public func removeVertex(vet: Vertex) {
         if adjList[vet] == nil {
             fatalError("参数错误")
         }
@@ -71,7 +71,7 @@ class GraphAdjList {
     }
 
     /* 打印邻接表 */
-    func print() {
+    public func print() {
         Swift.print("邻接表 =")
         for entry in adjList {
             var tmp: [Int] = []
@@ -83,12 +83,14 @@ class GraphAdjList {
     }
 }
 
+#if !TARGET
+
 @main
 enum GraphAdjacencyList {
     /* Driver Code */
     static func main() {
         /* 初始化无向图 */
-        let v = Vertex.valsToVets([1, 3, 2, 5, 4])
+        let v = Vertex.valsToVets(vals: [1, 3, 2, 5, 4])
         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]]]
         let graph = GraphAdjList(edges: edges)
         print("\n初始化后，图为")
@@ -119,3 +121,5 @@ enum GraphAdjacencyList {
         graph.print()
     }
 }
+
+#endif

codes/swift/chapter_graph/graph_adjacency_list_target.swift

@@ -0,0 +1 @@
+graph_adjacency_list.swift

codes/swift/chapter_graph/graph_bfs.swift

@@ -0,0 +1,56 @@
+/**
+ * File: graph_bfs.swift
+ * Created Time: 2023-02-21
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+import graph_adjacency_list_target
+import utils
+
+/* 广度优先遍历 BFS */
+// 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
+func graphBFS(graph: GraphAdjList, startVet: Vertex) -> [Vertex] {
+    // 顶点遍历序列
+    var res: [Vertex] = []
+    // 哈希表，用于记录已被访问过的顶点
+    var visited: Set<Vertex> = [startVet]
+    // 队列用于实现 BFS
+    var que: [Vertex] = [startVet]
+    // 以顶点 vet 为起点，循环直至访问完所有顶点
+    while !que.isEmpty {
+        let vet = que.removeFirst() // 队首顶点出队
+        res.append(vet) // 记录访问顶点
+        // 遍历该顶点的所有邻接顶点
+        for adjVet in graph.adjList[vet] ?? [] {
+            if visited.contains(adjVet) {
+                continue // 跳过已被访问过的顶点
+            }
+            que.append(adjVet) // 只入队未访问的顶点
+            visited.insert(adjVet) // 标记该顶点已被访问
+        }
+    }
+    // 返回顶点遍历序列
+    return res
+}
+
+@main
+enum GraphBFS {
+    /* Driver Code */
+    static func main() {
+        /* 初始化无向图 */
+        let v = Vertex.valsToVets(vals: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
+        let 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]],
+        ]
+        let graph = GraphAdjList(edges: edges)
+        print("\n初始化后，图为")
+        graph.print()
+
+        /* 广度优先遍历 BFS */
+        let res = graphBFS(graph: graph, startVet: v[0])
+        print("\n广度优先遍历（BFS）顶点序列为")
+        print(Vertex.vetsToVals(vets: res))
+    }
+}

codes/swift/chapter_graph/graph_dfs.swift

@@ -0,0 +1,54 @@
+/**
+ * File: graph_dfs.swift
+ * Created Time: 2023-02-21
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+import graph_adjacency_list_target
+import utils
+
+/* 深度优先遍历 DFS 辅助函数 */
+func dfs(graph: GraphAdjList, visited: inout Set<Vertex>, res: inout [Vertex], vet: Vertex) {
+    res.append(vet) // 记录访问顶点
+    visited.insert(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 // 跳过已被访问过的顶点
+        }
+        // 递归访问邻接顶点
+        dfs(graph: graph, visited: &visited, res: &res, vet: adjVet)
+    }
+}
+
+/* 深度优先遍历 DFS */
+// 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
+func graphDFS(graph: GraphAdjList, startVet: Vertex) -> [Vertex] {
+    // 顶点遍历序列
+    var res: [Vertex] = []
+    // 哈希表，用于记录已被访问过的顶点
+    var visited: Set<Vertex> = []
+    dfs(graph: graph, visited: &visited, res: &res, vet: startVet)
+    return res
+}
+
+@main
+enum GraphDFS {
+    /* Driver Code */
+    static func main() {
+        /* 初始化无向图 */
+        let v = Vertex.valsToVets(vals: [0, 1, 2, 3, 4, 5, 6])
+        let edges = [
+            [v[0], v[1]], [v[0], v[3]], [v[1], v[2]],
+            [v[2], v[5]], [v[4], v[5]], [v[5], v[6]],
+        ]
+        let graph = GraphAdjList(edges: edges)
+        print("\n初始化后，图为")
+        graph.print()
+
+        /* 深度优先遍历 DFS */
+        let res = graphDFS(graph: graph, startVet: v[0])
+        print("\n深度优先遍历（DFS）顶点序列为")
+        print(Vertex.vetsToVals(vets: res))
+    }
+}