NigelJu

class Solution {
    func majorityElement(_ nums: [Int]) -> Int {
        if nums.count == 1 {
            return nums.first!
        }
        var valueOccurCount = [Int: Int]()
        for num in nums {
            if let value = valueOccurCount[num] {
                if value + 1 > (nums.count / 2) {
                    return num

NigelJu

class Solution {
    func fizzBuzz(_ n: Int) -> [String] {
        var results = [String]()
        for index in 1 ... n {
            if n % 3 == 0 && n % 5 == 0 {
                results.append("FizzBuzz")
            }else if n % 3 == 0 {
                results.append("Fizz")
            }else if n % 5 == 0 {
                 results.append("Buzz")

NigelJu

class Solution {
    func isPowerOfTwo(_ n: Int) -> Bool {
        
        if n == 1 { return true }
        var sum = 1
        while sum < n {
            sum *= 2
        }
        return sum == n
    }

NigelJu

class Solution {
    func missingNumber(_ nums: [Int]) -> Int {
        if nums.count == 1 {
            if nums.first == 1 {
                return 0
            }
            return nums.first! + 1
        }
        let sortedNums = nums.sorted()
        if sortedNums.min() != 0 {

NigelJu

class Solution {
    func isPalindrome(_ s: String) -> Bool {
        var letters = [String]()
        
        for char in s {
            guard let charAsciiCode = UnicodeScalar(String(char))?.value,
                charAsciiCode >= 97 && charAsciiCode <= 122 || charAsciiCode >= 65 && charAsciiCode <= 90 || charAsciiCode >= 48 && charAsciiCode <= 57
                else { continue }
            letters.append(String(char))
        }

NigelJu

class Solution {
    func climbStairs(_ n: Int) -> Int {
        var fibs = [0, 1, 1]
        for index in 1 ... n+1 {
            if index <= 2 {
                continue
            }
            fibs.append(fibs[index - 1] + fibs[index - 2])

        }

NigelJu

class Solution {
    func climbStairs(_ n: Int) -> Int {

        if n == 0 {
            return 1
        }else if n < 0 {
            return 0
        }
        
        return climbStairs(n - 1) + climbStairs(n - 2)

NigelJu

class Solution {
    func climbStairs(_ n: Int) -> Int {

        if n == 0 {
            return 1
        }else if n < 0 {
            return 0
        }
        
        return climbStairs(n - 1) + climbStairs(n - 2)

NigelJu

class Solution {
    func climbStairs(_ n: Int) -> Int {
        var climbForOneStep = 0
        var climbForTwoStep = 0
        if n == 0 {
            return 1
        }
        if n >= 1 {
            climbForOneStep = climbStairs(n - 1)
        }

NigelJu

class Solution {
    func isIsomorphic(_ s: String, _ t: String) -> Bool {
        
        let sChars = Array(s)
        let tChars = Array(t)
        
        var mappingCharCodes = [Character: Character]()
        var backMappingCharCodes = [Character: Character]()
        
        if s.count == 0 { return true }