// nums is passed in by reference. (i.e., without making a copy)int len = removeElement(nums, val);
// any modification to nums in your function would be known by the caller.// using the length returned by your function, it prints the first len elements.for (int i = 0; i < len; i++) {    print(nums[i]);}

Input: nums = [3,2,2,3], val = 3Output: 2, nums = [2,2]Explanation: Your function should return length = 2, with the first two elements of nums being 2.It doesn't matter what you leave beyond the returned length. For example if you return 2 with nums = [2,2,3,3] or nums = [2,2,0,0], your answer will be accepted.

Input: nums = [0,1,2,2,3,0,4,2], val = 2Output: 5, nums = [0,1,4,0,3]Explanation: Your function should return length = 5, with the first five elements of nums containing 0, 1, 3, 0, and 4. Note that the order of those five elements can be arbitrary. It doesn't matter what values are set beyond the returned length.

0 <= nums.length <= 1000 <= nums[i] <= 500 <= val <= 100

class Solution {    public int removeElement(int[] nums, int val) {        // check edge        if (nums == null || nums.length == 0) {            return 0;        }        int index = 0;        for(int i = 0; i < nums.length; i++) {            if (nums[i] != val) {                nums[index] = nums[i];                index++;            }        }                return index;    }}

class Solution {    public int removeElement(int[] nums, int val) {        // check edge        if (nums == null || nums.length == 0) {            return 0;        }        int index = 0;        int n = nums.length - 1;        while (index <= n) {            if (nums[index] == val) {                nums[index] = nums[n];                nums[n] = val;                n--;            } else {                index++;            }        }                return index;    }}

# Uncomment the next line to define a global platform for your project# platform :ios, '9.0'
target 'RXSwiftDemo' do  # Comment the next line if you don't want to use dynamic frameworks  use_frameworks!
  # Pods for RXSwiftDemo  pod 'RxSwift', '6.1.0'  pod 'RxCocoa', '6.1.0'
  target 'RXSwiftDemoUITests' do    pod 'RxBlocking', '6.1.0'    pod 'RxTest', '6.1.0'  end
end

 let one = 1  let two = 2  let three = 3  /// This is a singe element observable  let observable: Observable<Int> = Observable<Int>.just(one)    /// This is an observable of individual type instances from a array  let observable2 = Observable.of(one, two, three)    /// This is an observables array using of to create  let observable3 = Observable.of([one, two, three])    /// This is an observable of individual type instances from a array  let observable4 = Observable.from([one, two, three])

let one = 1  let two = 2  let three = 3  /// This is an observable of individual type instances from a array  let observable = Observable.of(one, two, three)    /// Subscribes an element handler  observable.subscribe(onNext: { element in    print(element) // Result will be: 1,2,3  })    /// Subscribes an event handler to an observable sequence.  observable.subscribe { event in    print(event) // Result will be: next(1) next(2) next(3) completed  }

let observable = Observable<Void>.empty()    observable      .subscribe(        onNext: { element in          print(element)      },        /// When empty an observable, it will go to completed block        onCompleted: {          print("Completed")      }    )

/// If never an observable, it will not emit anythinglet observable = Observable<Any>.never()    observable      .subscribe(        onNext: { element in          print(element)      },        onCompleted: {          print("Completed")      }    )

let observable = Observable.of("A", "B", "C")  let subscription = observable.subscribe { event in    print(event)  }  /// When dispose, the observable can not emit anything  subscription.dispose()

let disposeBag = DisposeBag()        Observable.of("A", "B", "C")            .subscribe {            print($0)            }.disposed(by: disposeBag)

let disposeBag = DisposeBag()Observable<String>.create { (observer) -> Disposable in            observer.onNext("1")            observer.onNext("?")                        return Disposables.create()        }.subscribe(            onNext: { print($0) },            onError: { print($0) },            onCompleted: { print("Completed") })        .disposed(by: disposeBag)

let disposeBag = DisposeBag()var flip = false                let factory: Observable<Int> = Observable.deferred { () -> Observable<Int> in            flip = !flip                        if flip {                return Observable.of(1, 2, 3)            } else {                return Observable.of(4, 5, 6)            }        }                for _ in 0...1 {            factory.subscribe(onNext: {                print($0, terminator: " ... ")            }).disposed(by: disposeBag)            print()        }