[sorts] #algorithms #sorting

buble_sort.py

# https://www.geeksforgeeks.org/bubble-sort

def bubbleSort(arr): 
  	n = len(arr) 
    # Traverse through all array elements 
    for i in range(n) : 
      	# Last i elements are already in place 
      	for j in range(0, n-i-1) : 
            # traverse the array from 0 to n-i-1 
            # Swap if the element found is greater than the next element 
        	if arr[j] > arr[j+1] : 
          		arr[j], arr[j+1] = arr[j+1], arr[j]

insertion_sort.cpp

/* 
	C program for insertion sort 
    https://www.geeksforgeeks.org/insertion-sort
*/

#include <math.h> 
#include <stdio.h> 
  
/* Function to sort an array using insertion sort*/
void insertionSort(int arr[], int n) 
{ 
    int i, key, j; 
    for (i = 1; i < n; i++) { 
        key = arr[i]; 
        j = i - 1; 
  
        /* Move elements of arr[0..i-1], that are 
          greater than key, to one position ahead 
          of their current position */
        while (j >= 0 && arr[j] > key) { 
            arr[j + 1] = arr[j]; 
            j = j - 1; 
        } 
        arr[j + 1] = key; 
    } 
} 

merge_sort.cpp

/* 
	C program for Merge Sort 
	https://www.geeksforgeeks.org/merge-sort 
*/
#include<stdlib.h> 
#include<stdio.h> 
  
// Merges two subarrays of arr[]. 
// First subarray is arr[l..m] 
// Second subarray is arr[m+1..r] 
void merge(int arr[], int l, int m, int r){ 
    int i, j, k; 
    int n1 = m - l + 1; 
    int n2 =  r - m; 
  
    /* create temp arrays */
    int L[n1], R[n2]; 
  
    /* Copy data to temp arrays L[] and R[] */
    for (i = 0; i < n1; i++) 
        L[i] = arr[l + i]; 
    for (j = 0; j < n2; j++) 
        R[j] = arr[m + 1+ j]; 
  
    /* Merge the temp arrays back into arr[l..r]*/
    i = 0; // Initial index of first subarray 
    j = 0; // Initial index of second subarray 
    k = l; // Initial index of merged subarray 
    while (i < n1 && j < n2) 
    { 
        if (L[i] <= R[j]) 
        { 
            arr[k] = L[i]; 
            i++; 
        } 
        else
        { 
            arr[k] = R[j]; 
            j++; 
        } 
        k++; 
    } 
  
    /* Copy the remaining elements of L[], if there 
       are any */
    while (i < n1) 
    { 
        arr[k] = L[i]; 
        i++; 
        k++; 
    } 
  
    /* Copy the remaining elements of R[], if there 
       are any */
    while (j < n2) 
    { 
        arr[k] = R[j]; 
        j++; 
        k++; 
    } 
} 
  
/* l is for left index and r is right index of the 
   sub-array of arr to be sorted */
void mergeSort(int arr[], int l, int r) { 
    if (l < r) { 
        // Same as (l+r)/2, but avoids overflow for 
        // large l and h 
        int m = l+(r-l)/2; 
  
        // Sort first and second halves 
        mergeSort(arr, l, m); 
        mergeSort(arr, m+1, r); 
  
        merge(arr, l, m, r); 
    } 
} 

quick_sort.cpp

/* 
	C implementation QuickSort 
    https://www.geeksforgeeks.org/quick-sort
*/
#include<stdio.h> 

// 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 

	for (int j = low; j <= high- 1; j++) 
	{ 
		// If current element is smaller than or 
		// equal to 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++) 
		printf("%d ", arr[i]); 
	printf("n"); 
} 

// Driver program to test above functions 
int main() 
{ 
	int arr[] = {10, 7, 8, 9, 1, 5}; 
	int n = sizeof(arr)/sizeof(arr[0]); 
	quickSort(arr, 0, n-1); 
	printf("Sorted array: n"); 
	printArray(arr, n); 
	return 0; 
} 

selection_sort.cpp

/* 
	C program for implementation of selection sort 
    https://www.geeksforgeeks.org/selection-sort
*/
#include <stdio.h> 
  
void selectionSort(int arr[], int n){ 
    int i, j, min_idx; 
  
    // One by one move boundary of unsorted subarray 
    for (i = 0; i < n-1; i++){ 
        // Find the minimum element in unsorted array 
        min_idx = i; 
        for (j = i+1; j < n; j++) 
          if (arr[j] < arr[min_idx]) 
            min_idx = j; 
  
        // Swap the found minimum element with the first element 
        std::swap(arr[min_idx], arr[i]); 
    } 
}