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sendilkumarnsendilkumarn
committedSep 27, 2016
migrating radix-sort to swift3
1 parent f895ba1 commit ecbcfea

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‎Radix Tree/RadixTree.playground/Sources/RadixTree.swift

Lines changed: 19 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -85,7 +85,7 @@ public class Edge: Root {
8585
// For each child, erase it, then remove it from the children array.
8686
for _ in 0...children.count-1 {
8787
children[0].erase()
88-
children.removeAtIndex(0)
88+
children.remove(at: 0)
8989
}
9090
}
9191
}
@@ -137,7 +137,7 @@ public class RadixTree {
137137
}
138138

139139
// Inserts a string into the tree.
140-
public func insert(str: String) -> Bool {
140+
public func insert(_ str: String) -> Bool {
141141
//Account for a blank input. The empty string is already in the tree.
142142
if str == "" {
143143
return false
@@ -182,9 +182,9 @@ public class RadixTree {
182182
currEdge = e
183183
var tempIndex = searchStr.startIndex
184184
for _ in 1...shared.characters.count {
185-
tempIndex = tempIndex.successor()
185+
tempIndex = searchStr.characters.index(after: tempIndex)
186186
}
187-
searchStr = searchStr.substringFromIndex(tempIndex)
187+
searchStr = searchStr.substring(from: tempIndex)
188188
found = true
189189
break
190190
}
@@ -197,13 +197,13 @@ public class RadixTree {
197197

198198
// Create index objects and move them to after the shared prefix
199199
for _ in 1...shared.characters.count {
200-
index = index.successor()
201-
labelIndex = labelIndex.successor()
200+
index = searchStr.characters.index(after: index)
201+
labelIndex = e.label.characters.index(after: labelIndex)
202202
}
203203

204204
// Substring both the search string and the label from the shared prefix
205-
searchStr = searchStr.substringFromIndex(index)
206-
e.label = e.label.substringFromIndex(labelIndex)
205+
searchStr = searchStr.substring(from: index)
206+
e.label = e.label.substring(from: labelIndex)
207207

208208
// Create 2 new edges and update parent/children values
209209
let newEdge = Edge(e.label)
@@ -236,7 +236,7 @@ public class RadixTree {
236236
}
237237

238238
// Tells you if a string is in the tree
239-
public func find(str: String) -> Bool {
239+
public func find(_ str: String) -> Bool {
240240
// A radix tree always contains the empty string
241241
if str == "" {
242242
return true
@@ -267,9 +267,9 @@ public class RadixTree {
267267
currEdge = c
268268
var tempIndex = searchStr.startIndex
269269
for _ in 1...shared.characters.count {
270-
tempIndex = tempIndex.successor()
270+
tempIndex = searchStr.characters.index(after: tempIndex)
271271
}
272-
searchStr = searchStr.substringFromIndex(tempIndex)
272+
searchStr = searchStr.substring(from: tempIndex)
273273
found = true
274274
break
275275
}
@@ -300,12 +300,12 @@ public class RadixTree {
300300
}
301301

302302
// Removes a string from the tree
303-
public func remove(str: String) -> Bool {
303+
public func remove(_ str: String) -> Bool {
304304
// Removing the empty string removes everything in the tree
305305
if str == "" {
306306
for c in root.children {
307307
c.erase()
308-
root.children.removeAtIndex(0)
308+
root.children.remove(at: 0)
309309
}
310310
return true
311311
}
@@ -329,7 +329,7 @@ public class RadixTree {
329329
// and everything below it in the tree
330330
if currEdge.children[c].label == searchStr {
331331
currEdge.children[c].erase()
332-
currEdge.children.removeAtIndex(c)
332+
currEdge.children.remove(at: c)
333333
return true
334334
}
335335

@@ -341,9 +341,9 @@ public class RadixTree {
341341
currEdge = currEdge.children[c]
342342
var tempIndex = searchStr.startIndex
343343
for _ in 1...shared.characters.count {
344-
tempIndex = tempIndex.successor()
344+
tempIndex = searchStr.characters.index(after: tempIndex)
345345
}
346-
searchStr = searchStr.substringFromIndex(tempIndex)
346+
searchStr = searchStr.substring(from: tempIndex)
347347
found = true
348348
break
349349
}
@@ -364,15 +364,15 @@ public class RadixTree {
364364

365365
// Returns the prefix that is shared between the two input strings
366366
// i.e. sharedPrefix("court", "coral") -> "co"
367-
public func sharedPrefix(str1: String, _ str2: String) -> String {
367+
public func sharedPrefix(_ str1: String, _ str2: String) -> String {
368368
var temp = ""
369369
var c1 = str1.characters.startIndex
370370
var c2 = str2.characters.startIndex
371371
for _ in 0...min(str1.characters.count-1, str2.characters.count-1) {
372372
if str1[c1] == str2[c2] {
373373
temp.append( str1[c1] )
374-
c1 = c1.successor()
375-
c2 = c2.successor()
374+
c1 = str1.characters.index(after:c1)
375+
c2 = str2.characters.index(after:c2)
376376
} else {
377377
return temp
378378
}

‎Radix Tree/RadixTree.swift

Lines changed: 365 additions & 365 deletions
Original file line numberDiff line numberDiff line change
@@ -2,380 +2,380 @@ import Foundation
22

33
// The root is the top of the Radix Tree
44
public class Root {
5-
var children: [Edge]
6-
7-
public init() {
8-
children = [Edge]()
9-
}
10-
11-
// Returns the length (in number of edges) of the longest traversal down the tree.
12-
public func height() -> Int {
13-
// Base case: no children: the tree has a height of 1
14-
if children.count == 0 {
15-
return 1
16-
}
17-
// Recursion: find the max height of a root's child and return 1 + that max
18-
else {
19-
var max = 1
20-
for c in children {
21-
if c.height() > max {
22-
max = c.height()
23-
}
24-
}
25-
return 1 + max
26-
}
27-
}
28-
29-
// Returns how far down in the tree a Root/Edge is.
30-
// A root's level is always 0.
31-
public func level() -> Int {
32-
return 0
33-
}
34-
35-
// Prints the tree for debugging/visualization purposes.
36-
public func printRoot() {
37-
// Print the first half of the children
38-
if children.count > 1 {
39-
for c in 0...children.count/2-1 {
40-
children[c].printEdge()
41-
print("|")
42-
}
43-
} else if children.count > 0 {
44-
children[0].printEdge()
45-
}
46-
// Then print the root
47-
print("ROOT")
48-
// Print the second half of the children
49-
if children.count > 1 {
50-
for c in children.count/2...children.count-1 {
51-
children[c].printEdge()
52-
print("|")
53-
}
54-
}
55-
print()
56-
}
5+
var children: [Edge]
6+
7+
public init() {
8+
children = [Edge]()
9+
}
10+
11+
// Returns the length (in number of edges) of the longest traversal down the tree.
12+
public func height() -> Int {
13+
// Base case: no children: the tree has a height of 1
14+
if children.count == 0 {
15+
return 1
16+
}
17+
// Recursion: find the max height of a root's child and return 1 + that max
18+
else {
19+
var max = 1
20+
for c in children {
21+
if c.height() > max {
22+
max = c.height()
23+
}
24+
}
25+
return 1 + max
26+
}
27+
}
28+
29+
// Returns how far down in the tree a Root/Edge is.
30+
// A root's level is always 0.
31+
public func level() -> Int {
32+
return 0
33+
}
34+
35+
// Prints the tree for debugging/visualization purposes.
36+
public func printRoot() {
37+
// Print the first half of the children
38+
if children.count > 1 {
39+
for c in 0...children.count/2-1 {
40+
children[c].printEdge()
41+
print("|")
42+
}
43+
} else if children.count > 0 {
44+
children[0].printEdge()
45+
}
46+
// Then print the root
47+
print("ROOT")
48+
// Print the second half of the children
49+
if children.count > 1 {
50+
for c in children.count/2...children.count-1 {
51+
children[c].printEdge()
52+
print("|")
53+
}
54+
}
55+
print()
56+
}
5757
}
5858

5959
// Edges are what actually store the Strings in the tree
6060
public class Edge: Root {
61-
var parent: Root?
62-
var label: String
63-
64-
public init(_ label: String) {
65-
self.label = label
66-
super.init()
67-
}
68-
69-
public override func level() -> Int {
70-
// Recurse up the tree incrementing level by one until the root is reached
71-
if parent != nil {
72-
return 1 + parent!.level()
73-
}
74-
// If an edge has no parent, it's level is one
75-
// NOTE: THIS SHOULD NEVER HAPPEN AS THE ROOT IS ALWAYS THE TOP OF THE TREE
76-
else {
77-
return 1
78-
}
79-
}
80-
81-
// Erases a specific edge (and all edges below it in the tree).
82-
public func erase() {
83-
self.parent = nil
84-
if children.count > 0 {
85-
// For each child, erase it, then remove it from the children array.
86-
for _ in 0...children.count-1 {
87-
children[0].erase()
88-
children.removeAtIndex(0)
89-
}
90-
}
91-
}
92-
93-
// Prints the tree for debugging/visualization purposes.
94-
public func printEdge() {
95-
// Print the first half of the edge's children
96-
if children.count > 1 {
97-
for c in 0...children.count/2-1 {
98-
children[c].printEdge()
99-
}
100-
} else if children.count > 0 {
101-
children[0].printEdge()
102-
}
103-
// Tab over once up to the edge's level
104-
for x in 1...level() {
105-
if x == level() {
106-
print("|------>", terminator: "")
107-
} else {
108-
print("| ", terminator: "")
109-
}
110-
}
111-
print(label)
112-
// Print the second half of the edge's children
113-
if children.count == 0 {
114-
for _ in 1...level() {
115-
print("| ", terminator: "")
116-
}
117-
print()
118-
}
119-
if children.count > 1 {
120-
for c in children.count/2...children.count-1 {
121-
children[c].printEdge()
122-
}
123-
}
124-
}
61+
var parent: Root?
62+
var label: String
63+
64+
public init(_ label: String) {
65+
self.label = label
66+
super.init()
67+
}
68+
69+
public override func level() -> Int {
70+
// Recurse up the tree incrementing level by one until the root is reached
71+
if parent != nil {
72+
return 1 + parent!.level()
73+
}
74+
// If an edge has no parent, it's level is one
75+
// NOTE: THIS SHOULD NEVER HAPPEN AS THE ROOT IS ALWAYS THE TOP OF THE TREE
76+
else {
77+
return 1
78+
}
79+
}
80+
81+
// Erases a specific edge (and all edges below it in the tree).
82+
public func erase() {
83+
self.parent = nil
84+
if children.count > 0 {
85+
// For each child, erase it, then remove it from the children array.
86+
for _ in 0...children.count-1 {
87+
children[0].erase()
88+
children.remove(at: 0)
89+
}
90+
}
91+
}
92+
93+
// Prints the tree for debugging/visualization purposes.
94+
public func printEdge() {
95+
// Print the first half of the edge's children
96+
if children.count > 1 {
97+
for c in 0...children.count/2-1 {
98+
children[c].printEdge()
99+
}
100+
} else if children.count > 0 {
101+
children[0].printEdge()
102+
}
103+
// Tab over once up to the edge's level
104+
for x in 1...level() {
105+
if x == level() {
106+
print("|------>", terminator: "")
107+
} else {
108+
print("| ", terminator: "")
109+
}
110+
}
111+
print(label)
112+
// Print the second half of the edge's children
113+
if children.count == 0 {
114+
for _ in 1...level() {
115+
print("| ", terminator: "")
116+
}
117+
print()
118+
}
119+
if children.count > 1 {
120+
for c in children.count/2...children.count-1 {
121+
children[c].printEdge()
122+
}
123+
}
124+
}
125125
}
126126

127127
public class RadixTree {
128-
var root: Root
129-
130-
public init() {
131-
root = Root()
132-
}
133-
134-
// Returns the height of the tree by calling the root's height function.
135-
public func height() -> Int {
136-
return root.height() - 1
137-
}
138-
139-
// Inserts a string into the tree.
140-
public func insert(str: String) -> Bool {
141-
//Account for a blank input. The empty string is already in the tree.
142-
if str == "" {
143-
return false
144-
}
145-
146-
// searchStr is the parameter of the function
147-
// it will be substringed as the function traverses down the tree
148-
var searchStr = str
149-
150-
// currEdge is the current Edge (or Root) in question
151-
var currEdge = root
152-
153-
while true {
154-
var found = false
155-
156-
// If the current Edge has no children then the remaining searchStr is
157-
// created as a child
158-
if currEdge.children.count == 0 {
159-
let newEdge = Edge(searchStr)
160-
currEdge.children.append(newEdge)
161-
newEdge.parent = currEdge
162-
return true
163-
}
164-
165-
// Loop through all of the children
166-
for e in currEdge.children {
167-
// Get the shared prefix between the child in question and the
168-
// search string
169-
let shared = sharedPrefix(searchStr, e.label)
170-
var index = shared.startIndex
171-
172-
// If the search string is equal to the shared string,
173-
// the string already exists in the tree
174-
if searchStr == shared {
175-
return false
176-
}
177-
178-
// If the child's label is equal to the shared string, you have to
179-
// traverse another level down the tree, so substring the search
180-
// string, break the loop, and run it back
181-
else if shared == e.label {
182-
currEdge = e
183-
var tempIndex = searchStr.startIndex
184-
for _ in 1...shared.characters.count {
185-
tempIndex = tempIndex.successor()
186-
}
187-
searchStr = searchStr.substringFromIndex(tempIndex)
188-
found = true
189-
break
190-
}
191-
192-
// If the child's label and the search string share a partial prefix,
193-
// then both the label and the search string need to be substringed
194-
// and a new branch needs to be created
195-
else if shared.characters.count > 0 {
196-
var labelIndex = e.label.characters.startIndex
197-
198-
// Create index objects and move them to after the shared prefix
199-
for _ in 1...shared.characters.count {
200-
index = index.successor()
201-
labelIndex = labelIndex.successor()
202-
}
203-
204-
// Substring both the search string and the label from the shared prefix
205-
searchStr = searchStr.substringFromIndex(index)
206-
e.label = e.label.substringFromIndex(labelIndex)
207-
208-
// Create 2 new edges and update parent/children values
209-
let newEdge = Edge(e.label)
210-
e.label = shared
211-
for ec in e.children {
212-
newEdge.children.append(ec)
213-
}
214-
newEdge.parent = e
215-
e.children.removeAll()
216-
for nec in newEdge.children {
217-
nec.parent = newEdge
218-
}
219-
e.children.append(newEdge)
220-
let newEdge2 = Edge(searchStr)
221-
newEdge2.parent = e
222-
e.children.append(newEdge2)
223-
return true
224-
}
225-
// If they don't share a prefix, go to next child
226-
}
227-
228-
// If none of the children share a prefix, you have to create a new child
229-
if !found {
230-
let newEdge = Edge(searchStr)
231-
currEdge.children.append(newEdge)
232-
newEdge.parent = currEdge
233-
return true
234-
}
235-
}
236-
}
237-
238-
// Tells you if a string is in the tree
239-
public func find(str: String) -> Bool {
240-
// A radix tree always contains the empty string
241-
if str == "" {
242-
return true
243-
}
244-
// If there are no children then the string cannot be in the tree
245-
else if root.children.count == 0 {
246-
return false
247-
}
248-
var searchStr = str
249-
var currEdge = root
250-
while true {
251-
var found = false
252-
// Loop through currEdge's children
253-
for c in currEdge.children {
254-
// First check if the search string and the child's label are equal
255-
// if so the string is in the tree, return true
256-
if searchStr == c.label {
257-
return true
258-
}
259-
260-
// If that is not true, find the shared string b/t the search string
261-
// and the label
262-
let shared = sharedPrefix(searchStr, c.label)
263-
264-
// If the shared string is equal to the label, update the curent node,
265-
// break the loop, and run it back
266-
if shared == c.label {
267-
currEdge = c
268-
var tempIndex = searchStr.startIndex
269-
for _ in 1...shared.characters.count {
270-
tempIndex = tempIndex.successor()
271-
}
272-
searchStr = searchStr.substringFromIndex(tempIndex)
273-
found = true
274-
break
275-
}
276-
277-
// If the shared string is empty, go to the next child
278-
else if shared.characters.count == 0 {
279-
continue
280-
}
281-
282-
// If the shared string matches the search string, return true
283-
else if shared == searchStr {
284-
return true
285-
}
286-
287-
// If the search string and the child's label only share some characters,
288-
// the string is not in the tree, return false
289-
else if shared[shared.startIndex] == c.label[c.label.startIndex] &&
290-
shared.characters.count < c.label.characters.count {
291-
return false
292-
}
293-
}
294-
295-
// If nothing was found, return false
296-
if !found {
297-
return false
298-
}
299-
}
300-
}
301-
302-
// Removes a string from the tree
303-
public func remove(str: String) -> Bool {
304-
// Removing the empty string removes everything in the tree
305-
if str == "" {
306-
for c in root.children {
307-
c.erase()
308-
root.children.removeAtIndex(0)
309-
}
310-
return true
311-
}
312-
// If the tree is empty, you cannot remove anything
313-
else if root.children.count == 0 {
314-
return false
315-
}
316-
317-
var searchStr = str
318-
var currEdge = root
319-
while true {
320-
var found = false
321-
// If currEdge has no children, then the searchStr is not in the tree
322-
if currEdge.children.count == 0 {
323-
return false
324-
}
325-
326-
// Loop through the children
327-
for c in 0...currEdge.children.count-1 {
328-
// If the child's label matches the search string, remove that child
329-
// and everything below it in the tree
330-
if currEdge.children[c].label == searchStr {
331-
currEdge.children[c].erase()
332-
currEdge.children.removeAtIndex(c)
333-
return true
334-
}
335-
336-
// Find the shared string
337-
let shared = sharedPrefix(searchStr, currEdge.children[c].label)
338-
339-
// If the shared string is equal to the child's string, go down a level
340-
if shared == currEdge.children[c].label {
341-
currEdge = currEdge.children[c]
342-
var tempIndex = searchStr.startIndex
343-
for _ in 1...shared.characters.count {
344-
tempIndex = tempIndex.successor()
345-
}
346-
searchStr = searchStr.substringFromIndex(tempIndex)
347-
found = true
348-
break
349-
}
350-
}
351-
352-
// If there is no match, then the searchStr is not in the tree
353-
if !found {
354-
return false
355-
}
356-
}
357-
}
358-
359-
// Prints the tree by calling the root's print function
360-
public func printTree() {
361-
root.printRoot()
362-
}
128+
var root: Root
129+
130+
public init() {
131+
root = Root()
132+
}
133+
134+
// Returns the height of the tree by calling the root's height function.
135+
public func height() -> Int {
136+
return root.height() - 1
137+
}
138+
139+
// Inserts a string into the tree.
140+
public func insert(_ str: String) -> Bool {
141+
//Account for a blank input. The empty string is already in the tree.
142+
if str == "" {
143+
return false
144+
}
145+
146+
// searchStr is the parameter of the function
147+
// it will be substringed as the function traverses down the tree
148+
var searchStr = str
149+
150+
// currEdge is the current Edge (or Root) in question
151+
var currEdge = root
152+
153+
while true {
154+
var found = false
155+
156+
// If the current Edge has no children then the remaining searchStr is
157+
// created as a child
158+
if currEdge.children.count == 0 {
159+
let newEdge = Edge(searchStr)
160+
currEdge.children.append(newEdge)
161+
newEdge.parent = currEdge
162+
return true
163+
}
164+
165+
// Loop through all of the children
166+
for e in currEdge.children {
167+
// Get the shared prefix between the child in question and the
168+
// search string
169+
let shared = sharedPrefix(searchStr, e.label)
170+
var index = shared.startIndex
171+
172+
// If the search string is equal to the shared string,
173+
// the string already exists in the tree
174+
if searchStr == shared {
175+
return false
176+
}
177+
178+
// If the child's label is equal to the shared string, you have to
179+
// traverse another level down the tree, so substring the search
180+
// string, break the loop, and run it back
181+
else if shared == e.label {
182+
currEdge = e
183+
var tempIndex = searchStr.startIndex
184+
for _ in 1...shared.characters.count {
185+
tempIndex = searchStr.characters.index(after: tempIndex)
186+
}
187+
searchStr = searchStr.substring(from: tempIndex)
188+
found = true
189+
break
190+
}
191+
192+
// If the child's label and the search string share a partial prefix,
193+
// then both the label and the search string need to be substringed
194+
// and a new branch needs to be created
195+
else if shared.characters.count > 0 {
196+
var labelIndex = e.label.characters.startIndex
197+
198+
// Create index objects and move them to after the shared prefix
199+
for _ in 1...shared.characters.count {
200+
index = searchStr.characters.index(after: index)
201+
labelIndex = e.label.characters.index(after: labelIndex)
202+
}
203+
204+
// Substring both the search string and the label from the shared prefix
205+
searchStr = searchStr.substring(from: index)
206+
e.label = e.label.substring(from: labelIndex)
207+
208+
// Create 2 new edges and update parent/children values
209+
let newEdge = Edge(e.label)
210+
e.label = shared
211+
for ec in e.children {
212+
newEdge.children.append(ec)
213+
}
214+
newEdge.parent = e
215+
e.children.removeAll()
216+
for nec in newEdge.children {
217+
nec.parent = newEdge
218+
}
219+
e.children.append(newEdge)
220+
let newEdge2 = Edge(searchStr)
221+
newEdge2.parent = e
222+
e.children.append(newEdge2)
223+
return true
224+
}
225+
// If they don't share a prefix, go to next child
226+
}
227+
228+
// If none of the children share a prefix, you have to create a new child
229+
if !found {
230+
let newEdge = Edge(searchStr)
231+
currEdge.children.append(newEdge)
232+
newEdge.parent = currEdge
233+
return true
234+
}
235+
}
236+
}
237+
238+
// Tells you if a string is in the tree
239+
public func find(_ str: String) -> Bool {
240+
// A radix tree always contains the empty string
241+
if str == "" {
242+
return true
243+
}
244+
// If there are no children then the string cannot be in the tree
245+
else if root.children.count == 0 {
246+
return false
247+
}
248+
var searchStr = str
249+
var currEdge = root
250+
while true {
251+
var found = false
252+
// Loop through currEdge's children
253+
for c in currEdge.children {
254+
// First check if the search string and the child's label are equal
255+
// if so the string is in the tree, return true
256+
if searchStr == c.label {
257+
return true
258+
}
259+
260+
// If that is not true, find the shared string b/t the search string
261+
// and the label
262+
let shared = sharedPrefix(searchStr, c.label)
263+
264+
// If the shared string is equal to the label, update the curent node,
265+
// break the loop, and run it back
266+
if shared == c.label {
267+
currEdge = c
268+
var tempIndex = searchStr.startIndex
269+
for _ in 1...shared.characters.count {
270+
tempIndex = searchStr.characters.index(after: tempIndex)
271+
}
272+
searchStr = searchStr.substring(from: tempIndex)
273+
found = true
274+
break
275+
}
276+
277+
// If the shared string is empty, go to the next child
278+
else if shared.characters.count == 0 {
279+
continue
280+
}
281+
282+
// If the shared string matches the search string, return true
283+
else if shared == searchStr {
284+
return true
285+
}
286+
287+
// If the search string and the child's label only share some characters,
288+
// the string is not in the tree, return false
289+
else if shared[shared.startIndex] == c.label[c.label.startIndex] &&
290+
shared.characters.count < c.label.characters.count {
291+
return false
292+
}
293+
}
294+
295+
// If nothing was found, return false
296+
if !found {
297+
return false
298+
}
299+
}
300+
}
301+
302+
// Removes a string from the tree
303+
public func remove(_ str: String) -> Bool {
304+
// Removing the empty string removes everything in the tree
305+
if str == "" {
306+
for c in root.children {
307+
c.erase()
308+
root.children.remove(at: 0)
309+
}
310+
return true
311+
}
312+
// If the tree is empty, you cannot remove anything
313+
else if root.children.count == 0 {
314+
return false
315+
}
316+
317+
var searchStr = str
318+
var currEdge = root
319+
while true {
320+
var found = false
321+
// If currEdge has no children, then the searchStr is not in the tree
322+
if currEdge.children.count == 0 {
323+
return false
324+
}
325+
326+
// Loop through the children
327+
for c in 0...currEdge.children.count-1 {
328+
// If the child's label matches the search string, remove that child
329+
// and everything below it in the tree
330+
if currEdge.children[c].label == searchStr {
331+
currEdge.children[c].erase()
332+
currEdge.children.remove(at: c)
333+
return true
334+
}
335+
336+
// Find the shared string
337+
let shared = sharedPrefix(searchStr, currEdge.children[c].label)
338+
339+
// If the shared string is equal to the child's string, go down a level
340+
if shared == currEdge.children[c].label {
341+
currEdge = currEdge.children[c]
342+
var tempIndex = searchStr.startIndex
343+
for _ in 1...shared.characters.count {
344+
tempIndex = searchStr.characters.index(after: tempIndex)
345+
}
346+
searchStr = searchStr.substring(from: tempIndex)
347+
found = true
348+
break
349+
}
350+
}
351+
352+
// If there is no match, then the searchStr is not in the tree
353+
if !found {
354+
return false
355+
}
356+
}
357+
}
358+
359+
// Prints the tree by calling the root's print function
360+
public func printTree() {
361+
root.printRoot()
362+
}
363363
}
364364

365365
// Returns the prefix that is shared between the two input strings
366366
// i.e. sharedPrefix("court", "coral") -> "co"
367-
public func sharedPrefix(str1: String, _ str2: String) -> String {
368-
var temp = ""
369-
var c1 = str1.characters.startIndex
370-
var c2 = str2.characters.startIndex
371-
for _ in 0...min(str1.characters.count-1, str2.characters.count-1) {
372-
if str1[c1] == str2[c2] {
373-
temp.append( str1[c1] )
374-
c1 = c1.successor()
375-
c2 = c2.successor()
376-
} else {
377-
return temp
378-
}
379-
}
380-
return temp
367+
public func sharedPrefix(_ str1: String, _ str2: String) -> String {
368+
var temp = ""
369+
var c1 = str1.characters.startIndex
370+
var c2 = str2.characters.startIndex
371+
for _ in 0...min(str1.characters.count-1, str2.characters.count-1) {
372+
if str1[c1] == str2[c2] {
373+
temp.append( str1[c1] )
374+
c1 = str1.characters.index(after:c1)
375+
c2 = str2.characters.index(after:c2)
376+
} else {
377+
return temp
378+
}
379+
}
380+
return temp
381381
}

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