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Simplify method names
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@goingreen
goingreen committed Feb 12, 2016
1 parent 475024e commit 4419a0d
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Showing 2 changed files with 67 additions and 48 deletions.
85 changes: 48 additions & 37 deletions Union-Find/UnioinFind.playground/Contents.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -7,102 +7,113 @@ public struct UnionFind<T: Hashable> {
private var size = [Int]()


public mutating func addSetWithElement(element: T) {
public mutating func addSetWith(element: T) {
index[element] = parent.count
parent.append(parent.count)
size.append(1)
}

private mutating func findSetByIndexOfElement(index: Int) -> Int {
private mutating func setByIndex(index: Int) -> Int {
if parent[index] == index {
return index
} else {
parent[index] = findSetByIndexOfElement(parent[index])
parent[index] = setByIndex(parent[index])
return parent[index]
}
}

public mutating func findSetOfElement(element: T) -> Int? {
public mutating func setOf(element: T) -> Int? {
if let indexOfElement = index[element] {
return findSetByIndexOfElement(indexOfElement)
return setByIndex(indexOfElement)
} else {
return nil
}
}

public mutating func unionSetsWithElement(firstElement: T, andSecondElement secondElement: T) {
if let firstSet = findSetOfElement(firstElement), secondSet = findSetOfElement(secondElement) {
if (firstSet != secondSet) {
if (size[firstSet] < size[secondSet]) {
parent[firstSet] = secondSet;
public mutating func unionSetsContaining(firstElement: T, and secondElement: T) {
if let firstSet = setOf(firstElement), secondSet = setOf(secondElement) {
if firstSet != secondSet {
if size[firstSet] < size[secondSet] {
parent[firstSet] = secondSet
size[secondSet] += size[firstSet]
} else {
parent[secondSet] = firstSet;
parent[secondSet] = firstSet
size[firstSet] += size[secondSet]
}
}
}
}

public mutating func inSameSet(firstElement: T, and secondElement: T) -> Bool {
if let firstSet = setOf(firstElement), secondSet = setOf(secondElement) {
return firstSet == secondSet
} else {
return false
}
}
}


var dsu = UnionFind<Int>()

for i in 1...10 {
dsu.addSetWithElement(i)
dsu.addSetWith(i)
}
// now our dsu contains 10 independent sets

// let's divide our numbers into two sets by divisibility by 2
for i in 3...10 {
if i % 2 == 0 {
dsu.unionSetsWithElement(2, andSecondElement: i)
dsu.unionSetsContaining(2, and: i)
} else {
dsu.unionSetsWithElement(1, andSecondElement: i)
dsu.unionSetsContaining(1, and: i)
}
}

// check our division
print(dsu.findSetOfElement(2) == dsu.findSetOfElement(4))
print(dsu.findSetOfElement(4) == dsu.findSetOfElement(6))
print(dsu.findSetOfElement(6) == dsu.findSetOfElement(8))
print(dsu.findSetOfElement(8) == dsu.findSetOfElement(10))
print(dsu.inSameSet(2, and: 4))
print(dsu.inSameSet(4, and: 6))
print(dsu.inSameSet(6, and: 8))
print(dsu.inSameSet(8, and: 10))


print(dsu.inSameSet(1, and: 3))
print(dsu.inSameSet(3, and: 5))
print(dsu.inSameSet(5, and: 7))
print(dsu.inSameSet(7, and: 9))


print(dsu.findSetOfElement(1) == dsu.findSetOfElement(3))
print(dsu.findSetOfElement(3) == dsu.findSetOfElement(5))
print(dsu.findSetOfElement(5) == dsu.findSetOfElement(7))
print(dsu.findSetOfElement(7) == dsu.findSetOfElement(9))
print(dsu.inSameSet(7, and: 4))
print(dsu.inSameSet(3, and: 6))

print(dsu.findSetOfElement(8) == dsu.findSetOfElement(9))
print(dsu.findSetOfElement(4) == dsu.findSetOfElement(3))


var dsuForStrings = UnionFind<String>()
let words = ["all", "border", "boy", "afternoon", "amazing", "awesome", "best"]

dsuForStrings.addSetWithElement("a")
dsuForStrings.addSetWithElement("b")
dsuForStrings.addSetWith("a")
dsuForStrings.addSetWith("b")

// In that example we divide strings by its first letter
for word in words {
dsuForStrings.addSetWithElement(word)
dsuForStrings.addSetWith(word)
if word.hasPrefix("a") {
dsuForStrings.unionSetsWithElement("a", andSecondElement: word)
dsuForStrings.unionSetsContaining("a", and: word)
} else if word.hasPrefix("b") {
dsuForStrings.unionSetsWithElement("b", andSecondElement: word)
dsuForStrings.unionSetsContaining("b", and: word)
}
}

print(dsuForStrings.findSetOfElement("a") == dsuForStrings.findSetOfElement("all"))
print(dsuForStrings.findSetOfElement("all") == dsuForStrings.findSetOfElement("awesome"))
print(dsuForStrings.findSetOfElement("amazing") == dsuForStrings.findSetOfElement("afternoon"))
print(dsuForStrings.inSameSet("a", and: "all"))
print(dsuForStrings.inSameSet("all", and: "awesome"))
print(dsuForStrings.inSameSet("amazing", and: "afternoon"))

print(dsuForStrings.findSetOfElement("b") == dsuForStrings.findSetOfElement("boy"))
print(dsuForStrings.findSetOfElement("best") == dsuForStrings.findSetOfElement("boy"))
print(dsuForStrings.findSetOfElement("border") == dsuForStrings.findSetOfElement("best"))
print(dsuForStrings.inSameSet("b", and: "boy"))
print(dsuForStrings.inSameSet("best", and: "boy"))
print(dsuForStrings.inSameSet("border", and: "best"))

print(dsuForStrings.findSetOfElement("amazing") == dsuForStrings.findSetOfElement("boy"))
print(dsuForStrings.findSetOfElement("all") == dsuForStrings.findSetOfElement("border"))
print(dsuForStrings.inSameSet("amazing", and: "boy"))
print(dsuForStrings.inSameSet("all", and: "border"))



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30 changes: 19 additions & 11 deletions Union-Find/UnionFind.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,40 +15,48 @@ public struct UnionFind<T: Hashable> {
private var size = [Int]()


public mutating func addSetWithElement(element: T) {
public mutating func addSetWith(element: T) {
index[element] = parent.count
parent.append(parent.count)
size.append(1)
}

private mutating func findSetByIndexOfElement(index: Int) -> Int {
private mutating func setByIndex(index: Int) -> Int {
if parent[index] == index {
return index
} else {
parent[index] = findSetByIndexOfElement(parent[index])
parent[index] = setByIndex(parent[index])
return parent[index]
}
}

public mutating func findSetOfElement(element: T) -> Int? {
public mutating func setOf(element: T) -> Int? {
if let indexOfElement = index[element] {
return findSetByIndexOfElement(indexOfElement)
return setByIndex(indexOfElement)
} else {
return nil
}
}

public mutating func unionSetsWithElement(firstElement: T, andSecondElement secondElement: T) {
if let firstSet = findSetOfElement(firstElement), secondSet = findSetOfElement(secondElement) {
if (firstSet != secondSet) {
if (size[firstSet] < size[secondSet]) {
parent[firstSet] = secondSet;
public mutating func unionSetsContaining(firstElement: T, and secondElement: T) {
if let firstSet = setOf(firstElement), secondSet = setOf(secondElement) {
if firstSet != secondSet {
if size[firstSet] < size[secondSet] {
parent[firstSet] = secondSet
size[secondSet] += size[firstSet]
} else {
parent[secondSet] = firstSet;
parent[secondSet] = firstSet
size[firstSet] += size[secondSet]
}
}
}
}

public mutating func inSameSet(firstElement: T, and secondElement: T) -> Bool {
if let firstSet = setOf(firstElement), secondSet = setOf(secondElement) {
return firstSet == secondSet
} else {
return false
}
}
}

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