diff --git a/CPP/sorting/quicksort.cpp b/CPP/sorting/quicksort.cpp new file mode 100644 index 00000000..14b47b9e --- /dev/null +++ b/CPP/sorting/quicksort.cpp @@ -0,0 +1,73 @@ +/* C++ implementation of QuickSort */ +#include +using namespace std; + +// A utility function to swap two elements +void swap(int* a, int* b) +{ + int t = *a; + *a = *b; + *b = t; +} + +/* This function takes last element as pivot, places +the pivot element at its correct position in sorted +array, and places all smaller (smaller than pivot) +to left of pivot and all greater elements to right +of pivot */ +int partition(int arr[], int low, int high) +{ + int pivot = arr[high]; // pivot + int i + = (low + - 1); // Index of smaller element and indicates + // the right position of pivot found so far + + for (int j = low; j <= high - 1; j++) { + // If current element is smaller than the pivot + if (arr[j] < pivot) { + i++; // increment index of smaller element + swap(&arr[i], &arr[j]); + } + } + swap(&arr[i + 1], &arr[high]); + return (i + 1); +} + +/* The main function that implements QuickSort +arr[] --> Array to be sorted, +low --> Starting index, +high --> Ending index */ +void quickSort(int arr[], int low, int high) +{ + if (low < high) { + /* pi is partitioning index, arr[p] is now + at right place */ + int pi = partition(arr, low, high); + + // Separately sort elements before + // partition and after partition + quickSort(arr, low, pi - 1); + quickSort(arr, pi + 1, high); + } +} + +/* Function to print an array */ +void printArray(int arr[], int size) +{ + int i; + for (i = 0; i < size; i++) + cout << arr[i] << " "; + cout << endl; +} + +// Driver Code +int main() +{ + int arr[] = { 10, 7, 8, 9, 1, 5 }; + int n = sizeof(arr) / sizeof(arr[0]); + quickSort(arr, 0, n - 1); + cout << "Sorted array: \n"; + printArray(arr, n); + return 0; +}