Adding DFS

Author: aliHafizji

Topological Sort/Topological Sort.playground/Contents.swift

@@ -2,4 +2,27 @@
 
 import UIKit
 
-var str = "Hello, playground"
+let graph = Graph()
+
+let node5 = graph.addNode("5")
+let node7 = graph.addNode("7")
+let node3 = graph.addNode("3")
+let node11 = graph.addNode("11")
+let node8 = graph.addNode("8")
+let node2 = graph.addNode("2")
+let node9 = graph.addNode("9")
+let node10 = graph.addNode("10")
+
+graph.addEdge(fromNode: node5, toNode: node11)
+graph.addEdge(fromNode: node7, toNode: node11)
+graph.addEdge(fromNode: node7, toNode: node8)
+graph.addEdge(fromNode: node3, toNode: node8)
+graph.addEdge(fromNode: node3, toNode: node10)
+graph.addEdge(fromNode: node11, toNode: node2)
+graph.addEdge(fromNode: node11, toNode: node9)
+graph.addEdge(fromNode: node11, toNode: node10)
+graph.addEdge(fromNode: node8, toNode: node9)
+
+print(graph.description, terminator: "")
+
+graph.depthFirstSearch("5")

Topological Sort/Topological Sort.playground/Sources/Graph.swift

@@ -0,0 +1,56 @@
+
+public class Graph: CustomStringConvertible {
+  
+  private var adjacencyLists: [String : [String]]
+
+  public init() {
+    adjacencyLists = [String : [String]]()
+  }
+  
+  public func addNode(value: String) -> String {
+    adjacencyLists[value] = []
+    return value
+  }
+  
+  public func addEdge(fromNode from: String, toNode to: String) -> Bool {
+    adjacencyLists[from]?.append(to)
+    return adjacencyLists[from] != nil ? true : false
+  }
+  
+  public var description: String {
+    return adjacencyLists.description
+  }
+  
+  private func adjacencyList(forValue: String) -> [String]? {
+    for (key, adjacencyList) in adjacencyLists {
+      if key == forValue {
+        return adjacencyList
+      }
+    }
+    return nil
+  }
+}
+
+extension Graph {
+
+  public func depthFirstSearch(source: String) -> [String] {
+    var result = [String]()
+    var stack = Stack<String>()
+    
+    result.append(source)
+    stack.push(source)
+    
+    while !stack.isEmpty {
+      if let element = stack.pop(), temp = adjacencyList(element) {
+        for node in temp {
+          stack.push(node)
+          result.append(node)
+        }
+      }
+    }
+    
+    return result
+  }
+}
+
+

Topological Sort/Topological Sort.playground/Sources/Stack.swift

@@ -0,0 +1,39 @@
+import Foundation
+
+public struct Stack<T> {
+  private var array = [T]()
+  
+  public var isEmpty: Bool {
+    return array.isEmpty
+  }
+  
+  public var count: Int {
+    return array.count
+  }
+  
+  public mutating func push(element: T) {
+    array.append(element)
+  }
+  
+  public mutating func pop() -> T? {
+    if isEmpty {
+      return nil
+    } else {
+      return array.removeLast()
+    }
+  }
+  
+  public func peek() -> T? {
+    return array.last
+  }
+}
+
+extension Stack: SequenceType {
+  public func generate() -> AnyGenerator<T> {
+    var curr = self
+    return anyGenerator {
+      _ -> T? in
+      return curr.pop()
+    }
+  }
+}

Topological Sort/Topological Sort.playground/timeline.xctimeline

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Timeline
+   version = "3.0">
+   <TimelineItems>
+   </TimelineItems>
+</Timeline>