Update Shuffle

according to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle

`checks if j ≠ i may be omitted`, and also remove checking logic will optimise performance(tested by 100000 times random).

Author: passerbyloo

Shuffle/README.markdown

@@ -96,9 +96,6 @@ public func shuffledArray(_ n: Int) -> [Int] {
   var a = [Int](repeating: 0, count: n)
   for i in 0..<n {
     let j = Int.random(in: 0...i)
-    if i != j {
-      a[i] = a[j]
-    }
     a[j] = i
   }
   return a

Shuffle/Shuffle.swift

@@ -30,9 +30,6 @@ public func shuffledArray(_ n: Int) -> [Int] {
   var a = Array(repeating: 0, count: n)
   for i in 0..<n {
     let j = random(i + 1)
-    if i != j {
-      a[i] = a[j]
-    }
     a[j] = i  // insert next number from the sequence
   }
   return a