Naive Graphs Practice using Adjacency Matrix instead of normal linked lists

NaiveGraphs.swift

import Cocoa




class Graph {
    let size: Int
    private var nodes: [[Int]]
    
    init(size: Int) {
        self.size = size
        nodes = Array<[Int]>(repeating: [] , count: size)
    }
    
    func walkBFS(from target: Int) {
        var nodesToVisit = [Int]()
        var visitedNodes = Set<Int>()
        
        nodesToVisit  += nodes[target]
        visitedNodes.insert(target)
        print("Starting at: \(target)")
        while let next = nodesToVisit.first {
            print("Visiting Node: \(next)")
            visitedNodes.insert(next)
            nodesToVisit = Array(nodesToVisit.dropFirst())
            for item in nodes[next] where !visitedNodes.contains(item) {
                if nodesToVisit.contains(item) {
                    continue
                }
                nodesToVisit.append(item)
            }
        }
    }
    
    func walkDFS(from target: Int) {
        var nodesToVisit = [Int]()
        var visitedNodes = Set<Int>()
        
        nodesToVisit  += nodes[target]
        visitedNodes.insert(target)
        print("Starting at: \(target)")
        while let next = nodesToVisit.last {
            print("Visiting Node: \(next)")
            visitedNodes.insert(next)
            nodesToVisit = Array(nodesToVisit.dropLast())
            for item in nodes[next] where !visitedNodes.contains(item) {
                if nodesToVisit.contains(item) {
                    continue
                }
                nodesToVisit.append(item)
            }
        }
    }
    
    func attach(nodeA: Int, nodeB: Int) {
        nodes[nodeA].append(nodeB)
        nodes[nodeB].append(nodeA)
    }
    
    func show() {
        for (index, item) in nodes.enumerated() {
            print("Row: \(index) || \(item)")
        }
    }
}

let m = Graph(size: 8)
m.attach(nodeA: 0, nodeB: 3)
m.attach(nodeA: 3, nodeB: 1)
m.attach(nodeA: 3, nodeB: 2)
m.attach(nodeA: 1, nodeB: 0)
m.attach(nodeA: 1, nodeB: 5)
m.show()

print("------------------- BFS -----------------")
m.walkBFS(from: 0)


print("------------------- DFS -----------------")
m.walkDFS(from: 0)