Create qs.cpp

CPP/qs.cpp

@@ -0,0 +1,71 @@
+// C++ Implementation of the Quick Sort Algorithm.
+#include <iostream>
+using namespace std;
+
+int partition(int arr[], int start, int end)
+{
+
+	int pivot = arr[start];
+
+	int count = 0;
+	for (int i = start + 1; i <= end; i++) {
+		if (arr[i] <= pivot)
+			count++;
+	}
+
+	// Giving pivot element its correct position
+	int pivotIndex = start + count;
+	swap(arr[pivotIndex], arr[start]);
+
+	// Sorting left and right parts of the pivot element
+	int i = start, j = end;
+
+	while (i < pivotIndex && j > pivotIndex) {
+
+		while (arr[i] <= pivot) {
+			i++;
+		}
+
+		while (arr[j] > pivot) {
+			j--;
+		}
+
+		if (i < pivotIndex && j > pivotIndex) {
+			swap(arr[i++], arr[j--]);
+		}
+	}
+
+	return pivotIndex;
+}
+
+void quickSort(int arr[], int start, int end)
+{
+
+	// base case
+	if (start >= end)
+		return;
+
+	// partitioning the array
+	int p = partition(arr, start, end);
+
+	// Sorting the left part
+	quickSort(arr, start, p - 1);
+
+	// Sorting the right part
+	quickSort(arr, p + 1, end);
+}
+
+int main()
+{
+
+	int arr[] = { 9, 3, 4, 2, 1, 8 };
+	int n = 6;
+
+	quickSort(arr, 0, n - 1);
+
+	for (int i = 0; i < n; i++) {
+		cout << arr[i] << " ";
+	}
+
+	return 0;
+}