NigelJu

class Solution {
    func permute(_ nums: [Int]) -> [[Int]] {
        for num in nums {
            let index = nums.index(of: num)!
            var newNums = nums
            newNums.remove(at: index)
            dfs(a: [num], b: newNums)
        }
        return [[1]]
    }

NigelJu

class Solution {
    func reverse(_ x: Int) -> Int {
        let num = abs(x)
        let str = String(String(num).reversed())
        if let int = Int32(str) {
            return x > 0 ? Int(int) : 0 - Int(int)
        }
        
        return 0
        

NigelJu

class Solution {
    func wordPattern(_ pattern: String, _ str: String) -> Bool {
        
        let strArray = Array(str.split(separator: " "))
        let patternArray = Array(pattern)
 
        guard strArray.count == patternArray.count &&
            Set(pattern).count == Set(strArray).count else { return false }
            
        var mappingDict = [Character: Substring]()

NigelJu

class Solution {
    func rotate(_ nums: inout [Int], _ k: Int) {

        var stepCount = k % nums.count
        
        while stepCount > 0 && !nums.isEmpty {
            nums.insert(nums.last!, at: 0)
            nums.removeLast()
            
            

NigelJu

class Solution {
    func rotate(_ nums: inout [Int], _ k: Int) {
        var newNums = nums
        for index in 0 ..< newNums.count {
            newNums[(index + k) % newNums.count] = nums[index]   
        }
        nums = newNums
    }
}

NigelJu

class Solution {
    func rotate(_ nums: inout [Int], _ k: Int) {
        var stepCount = k
      
        while stepCount > 0 && !nums.isEmpty {
            nums.insert(nums.last!, at: 0)
            nums.removeLast()
            stepCount -= 1
        }
    }

NigelJu

class Solution {
    func isPerfectSquare(_ num: Int) -> Bool {
        var base = 1
        var tmp = 1
        repeat {
            tmp = base * base
            base += 1
        }while (tmp < num)
        return tmp == num
    }

NigelJu

class Solution {
    func rob(_ nums: [Int]) -> Int {
        if (nums.count == 1)
        {
            return nums[0]
        }
        var now = 0
        var last = 0
        for i in 0..<nums.count
        {

NigelJu

class Solution {
    func detectCapitalUse(_ word: String) -> Bool {
        
        let isLowerCase = word.lowercased() == word
        let isUpperCase = word.uppercased() == word
        if isLowerCase || isUpperCase { return true }
        
        var words = Array(word)
        let isFirstCapital = String((words.first!)).uppercased() == String(words.first!)
                

NigelJu

class Solution {
    func detectCapitalUse(_ word: String) -> Bool {
        
        var words = Array(word)
        let isFirstCapital = String((words.first!)).uppercased() == String(words.first!)
        let isLowerCase = word.lowercased() == word
        let isUpperCase = word.uppercased() == word
    
        if isLowerCase || isUpperCase { return true }