Add QuickSort implementation

Author: Nemanja

sort-algorithms/QuickSort.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"fmt"
+	"go-sort-algorithms/utils"
+)
+
+func QuickSort(items []int) {
+
+	stack := utils.Stack{}
+	stack.Push(0)
+	stack.Push(len(items) - 1)
+
+	for !stack.IsEmpty() {
+
+		endIndex := stack.Pop()
+		startIndex := stack.Pop()
+
+		partitionElementIndex := partition(items, startIndex, endIndex)
+
+		if partitionElementIndex - 1 > startIndex {
+			stack.Push(startIndex)
+			stack.Push(partitionElementIndex - 1)
+		}
+
+		if partitionElementIndex + 1 < endIndex {
+			stack.Push(partitionElementIndex + 1)
+			stack.Push(endIndex)
+		}
+	}
+
+}
+
+func partition(items []int, startIndex, endIndex int) int {
+
+	i := startIndex + 1
+	j := endIndex
+
+	for true {
+
+		for items[i] < items[startIndex] {
+			i++
+			if i == endIndex {
+				break
+			}
+		}
+
+		for items[startIndex] < items[j] {
+			j--
+			if j == startIndex {
+				break
+			}
+		}
+
+		if i >= j {
+			break
+		}
+		utils.Swap(items, i, j)
+	}
+	utils.Swap(items, startIndex, j)
+	return j
+}
+
+
+func main() {
+
+	numbers := utils.GetNumbers()
+	fmt.Println("Unsorted numbers", numbers)
+
+	QuickSort(numbers)
+	fmt.Println("Sorted numbers", numbers)
+}