Added new solutions with tests

Author: Michael-Ho-Bose

Easy/0007-ReverseInteger+0069-Sqrtx.playground/Contents.swift

@@ -1,26 +1,51 @@
 // LeetCode: https://leetcode.com/problems/reverse-integer/description/
+
 import Foundation
+import XCTest
 
 classSolution{
 func reverse(_ x:Int)->Int{
 vartemp=abs(x)
 varoutput=0
 while temp >0{
-vartail= temp %10
+output = output *10+ temp %10
  temp = temp /10
- output = output *10+ tail
-if(output >Int32.max || output <Int32.min){return0}
 }
-
-return output * x.signum() // Times back the sign of the original number
+guard output <Int32.max, output >Int32.min else{return0}
+return output * x.signum()
 }
 
 func mySqrt(_ x:Int)->Int{
 returnInt(sqrt(Double(x)))
-
 }
 }
 
-letsolution=Solution()
-print("\(solution.reverse(-123))")
-print("\(solution.mySqrt(8))")
+classTests:XCTestCase{
+letsolution=Solution()
+
+func testSample1(){
+letinput=-123
+letexpected=-321
+XCTAssertEqual(solution.reverse(input), expected)
+}
+
+func testSample2(){
+letinput=123
+letexpected=321
+XCTAssertEqual(solution.reverse(input), expected)
+}
+
+func testSample3(){
+letinput=120
+letexpected=21
+XCTAssertEqual(solution.reverse(input), expected)
+}
+
+func testSample4(){
+letinput=1534236469
+letexpected=0
+XCTAssertEqual(solution.reverse(input), expected)
+}
+}
+
+Tests.defaultTestSuite.run()

Medium/0017-LetterCombinationsOfAPhoneNumber.playground/Contents.swift

@@ -0,0 +1,44 @@
+// LeetCode: https://leetcode.com/problems/letter-combinations-of-a-phone-number/description/
+
+classSolution{
+func letterCombinations(_ digits:String)->[String]{
+varoutput:[String]=[]
+vardict=[
+"2":"abc",
+"3":"def",
+"4":"ghi",
+"5":"jkl",
+"6":"mno",
+"7":"pqrs",
+"8":"tuv",
+"9":"wxyz",
+]
+fordigitin digits {
+iflet str =dict[String(digit)]{
+appendStr(output:&output, toAppend: str)
+}
+}
+return output
+}
+
+func appendStr(output:inout[String], toAppend:String){
+if output.count ==0{
+forstrin toAppend {
+ output.append(String(str))
+}
+return
+}
+lettemp= output
+ output =[]
+forstrin toAppend {
+varcurrentOut= temp
+forindexin0..<currentOut.count {
+currentOut[index].append(str)
+ output.append(currentOut[index])
+}
+}
+}
+}
+
+letsolution=Solution()
+print(solution.letterCombinations("23")) // ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]

Medium/0017-LetterCombinationsOfAPhoneNumber.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playgroundversion='5.0'target-platform='macos'>
+ <timelinefileName='timeline.xctimeline'/>
+</playground>

Medium/0238-ProductOfArrayExceptSelf.playground/Contents.swift

@@ -0,0 +1,42 @@
+// LeetCode: https://leetcode.com/problems/product-of-array-except-self/description/
+
+import XCTest
+
+classSolution{
+func productExceptSelf(_ nums:[Int])->[Int]{
+varzeroCount=0
+varsum=1
+foriin nums {
+if i !=0{
+ sum = sum * i
+}else{
+ zeroCount +=1
+}
+}
+if zeroCount >1{
+return nums.map{ _ in0}
+}elseif zeroCount ==1{
+return nums.map{ $0 ==0? sum :0}
+}else{
+return nums.map{ sum / $0 }
+}
+}
+}
+
+classTests:XCTestCase{
+letsolution=Solution()
+
+func testSample1(){
+letinput=[1,2,3,4]
+letexpected=[24,12,8,6]
+XCTAssertEqual(solution.productExceptSelf(input), expected)
+}
+
+func testSample2(){
+letinput=[0,0]
+letexpected=[0,0]
+XCTAssertEqual(solution.productExceptSelf(input), expected)
+}
+}
+
+Tests.defaultTestSuite.run()

Medium/0238-ProductOfArrayExceptSelf.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playgroundversion='5.0'target-platform='macos'executeOnSourceChanges='false'>
+ <timelinefileName='timeline.xctimeline'/>
+</playground>

Udacity Practices/Closures.playground/Contents.swift

@@ -0,0 +1,60 @@
+// Swift GCD
+
+// Assign to var or constant
+letf={(x:Int)->Int
+in
+return x +42
+}
+
+f(9)
+f(76)
+
+// Closures in an array (or a dictionary, or a set, etc...)
+letclosures=[
+ f,
+{(x:Int)->Intinreturn x *2},
+{x inreturn x -8},
+{x in x*x},
+{$0 *42}
+]
+// $0 means position zero
+
+forfnin closures {
+fn(42)
+}
+
+// Functions and closures are exactly the same thing
+func foo(x:Int)->Int{
+return42+ x
+}
+
+letfoo={(x:Int)->Int
+in
+42+ x
+}
+
+foo(30)
+
+// MARK: - Typealias
+// Standard form: typealias newName = oldName
+typealiasInteger=Int
+
+// Useful when used with functions and closures
+// (Int) -> Int
+typealiasIntToInt=(Int)->Int
+typealiasIntMaker=()->Int
+
+func makeCounter()->IntMaker{
+varn=0
+
+func adder()->Int{
+ n = n +1
+return n
+}
+
+return adder
+}
+
+letcounter1=makeCounter()
+counter1()
+

Udacity Practices/Closures.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playgroundversion='5.0'target-platform='macos'>
+ <timelinefileName='timeline.xctimeline'/>
+</playground>