[Array] Optimize code style to Remove Duplicates from Sorted Array I and II

Author: soapyigu

Array/RemoveDuplicatesFromSortedArray.swift

@@ -7,19 +7,17 @@
 
 class RemoveDuplicatesFromSortedArray {
     func removeDuplicates(inout nums: [Int]) -> Int {
-        if nums.count <= 1 {
-            return nums.count
+        guard nums.count > 0 else {
+            return 0
         }
-    
-        var lastIndex = 0
 
-        for num in nums {
-            if num != nums[lastIndex] {
-                lastIndex += 1
-                nums[lastIndex] = num
-            }
+        var index = 0
+        
+        for num in nums where num != nums[index] {
+            index += 1
+            nums[index] = num
         }
 
-        return lastIndex + 1
+        return index + 1
     }
 }

Array/RemoveDuplicatesFromSortedArrayII.swift

@@ -8,19 +8,19 @@
 
 class RemoveDuplicatesFromSortedArrayII {
     func removeDuplicates(inout nums: [Int]) -> Int {
-        // edge case
-        if nums.count <= 2 {
+        guard nums.count > 2 else {
             return nums.count
         }
 
-        var lastIndex = 1
+        var index = 1
+        
         for i in 2..<nums.count {
-            if nums[lastIndex] != nums[i] || nums[lastIndex] != nums[lastIndex - 1] {
-                lastIndex += 1
-                nums[lastIndex] = nums[i]
-            }
+            if nums[index] != nums[index - 1] || nums[index] != nums[i] {
+                index += 1
+                nums[index] = nums[i]
+            } 
         }
 
-        return lastIndex + 1
+        return index + 1
     }
 }