Fix quick sort code.

Author: deepakhb2

lib/Algorithm-Sorting/quick_sort.rb

@@ -1,95 +1,89 @@
 # Best case: Omega(nlog(n))
 # Worst case: O(nlog(n))
 
-values = [5,2,4,8,7,1,3,6]
+class QuickSort
+  class << self
+    def swap(arr, first_index, second_index)
+      temp = arr[first_index]
+      arr[first_index] = arr[second_index]
+      arr[second_index] = temp
+    end
 
-def swap(arr, first_index, second_index)
-  temp = arr[first_index]
-  arr[first_index] = arr[second_index]
-  arr[second_index] = temp
-end
+    def l_pivot_partition(arr, left, right)
+      pivot_elem = arr[left]
+      partition_index = left+1
 
-def l_pivot_partition(arr, left, right)
-  pivot_elem = arr[left]
-  partition_index = left+1 
+      (left..right).each do |i|
+        if(arr[i] < pivot_elem)
+          swap(arr, i, partition_index)
+          partition_index += 1
+        end
+      end
+      swap(arr, left, partition_index-1)
+      partition_index-1
+    end
 
-  (left..right).each do |i|
-    if(arr[i] < pivot_elem)
-      swap(arr, i, partition_index)
-      partition_index += 1
+    def r_pivot_partition(arr, left, right)
+      pivot_elem = arr[right]
+      partition_index = left
+
+      (left..right).each do |i|
+        if(arr[i] < pivot_elem)
+          swap(arr, i, partition_index)
+          partition_index += 1
+        end
+      end
+      swap(arr, right, partition_index)
+      partition_index
     end
-  end
-  swap(arr, left, partition_index-1)
-  partition_index-1
-end
 
-def r_pivot_partition(arr, left, right)
-  pivot_elem = arr[right]
-  partition_index = left
+    def quick_sort(arr, left, right, left_pivot = true)
+      if(left < right)
+        partition_index = l_pivot_partition(arr, left, right) if left_pivot
+        partition_index = r_pivot_partition(arr, left, right) unless left_pivot
+        quick_sort(arr, left, partition_index-1, left_pivot)
+        quick_sort(arr, partition_index+1, right, left_pivot)
+      end
+      return arr
+    end
 
-  (left..right).each do |i|
-    if(arr[i] < pivot_elem)
-      swap(arr, i, partition_index)
-      partition_index += 1
+    def recursive(arr)
+      quick_sort(arr, 0, arr.size-1, true)
     end
-  end
-  swap(arr, right, partition_index)
-  partition_index
-end
 
-def quick_sort(arr, left, right, left_pivot = true)
-  if(left < right)
-    partition_index = l_pivot_partition(arr, left, right) if left_pivot
-    partition_index = r_pivot_partition(arr, left, right) unless left_pivot
-    quick_sort(arr, left, partition_index-1, left_pivot)
-    quick_sort(arr, partition_index+1, right, left_pivot)
-  end
-  return arr
-end
 
-p values
-p "Sort using first element as pivot: "
-p quick_sort(values, 0, values.size-1, true)
-values = [5,2,4,8,7,1,3,6]
-p "Sort using last element as pivot: "
-p quick_sort(values, 0, values.size-1, false)
+    def non_recursive(arr)
+      if(arr.size < 2)
+        return
+      end
 
+      left_array = []
+      right_array = []
+      pivot = arr[0]
 
-def order_quick_sort(arr)
-  if(arr.size < 2)
-    return
-  end
+      for i in (1...arr.size) do
+        if(arr[i] <= pivot)
+          left_array.push(arr[i])
+        else
+          right_array.push(arr[i])
+        end
+      end
+      order_quick_sort(left_array)
+      order_quick_sort(right_array)
 
-  left_array = []
-  right_array = []
-  pivot = arr[0]
+      index = 0
+      for j in (0...left_array.size) do
+        arr[index] = left_array[j]
+        index += 1
+      end
 
-  for i in (1...arr.size) do
-    if(arr[i] <= pivot)
-      left_array.push(arr[i])
-    else
-      right_array.push(arr[i])
-    end
-  end
-  order_quick_sort(left_array)
-  order_quick_sort(right_array)
-  
-  index = 0
-  for j in (0...left_array.size) do
-    arr[index] = left_array[j]
-    index += 1
-  end
+      arr[index] = pivot
+      index += 1
 
-  arr[index] = pivot
-  index += 1
-  
-  for k in (0...right_array.size) do
-    arr[index] = right_array[k]
-    index += 1
+      for k in (0...right_array.size) do
+        arr[index] = right_array[k]
+        index += 1
+      end
+    end
   end
 end
-
-values = [5,2,4,8,7,1,3,6]
-p "Sort using first element as pivot and retaining order: "
-order_quick_sort(values)
-p values