sorting Namespace Reference

Sorting algorithms. More...

Functions
template<typename T , size_t N>
std::array< T, N >	shuffle (std::array< T, N > arr)
template<typename T , size_t N>
std::array< T, N >	randomized_bogosort (std::array< T, N > arr)
template<typename T >
void	gnomeSort (T *arr, int size)
template<typename T , size_t size>
std::array< T, size >	gnomeSort (std::array< T, size > arr)
template<typename T >
void	insertionSort (T *arr, int n)
	Insertion Sort Function. More...
template<typename T >
void	insertionSort (std::vector< T > *arr)
template<class Iterator >
void	merge (Iterator l, Iterator r, const Iterator e, char b[])
	merges 2 sorted adjacent segments into a larger sorted segment More...
template<class Iterator >
void	non_recursive_merge_sort (const Iterator first, const Iterator last, const size_t n)
	bottom-up merge sort which sorts elements in a non-decreasing order More...
template<class Iterator >
void	non_recursive_merge_sort (const Iterator first, const size_t n)
	bottom-up merge sort which sorts elements in a non-decreasing order More...
template<class Iterator >
void	non_recursive_merge_sort (const Iterator first, const Iterator last)
	bottom-up merge sort which sorts elements in a non-decreasing order More...
template<std::size_t N>
std::array< int, N >	pigeonSort (std::array< int, N > arr)
int	partition (int arr[], int low, int high)
void	quickSort (int arr[], int low, int high)
template<typename T >
void	quicksort (std::vector< T > *arr, int32_t low, int32_t high)
template<typename T >
std::vector< T >	quicksort (std::vector< T > arr, int32_t low, int32_t high)
template<typename T >
void	recursive_bubble_sort (std::vector< T > *nums, uint64_t n)
	This is an implementation of the recursive_bubble_sort. A vector is passed to the function which is then dereferenced, so that the changes are reflected in the original vector. It also accepts a second parameter of type int and name n, which is the size of the array. More...
template<typename T >
void	shell_sort (T *arr, size_t LEN)
template<typename T , size_t N>
void	shell_sort (T(&arr)[N])
template<typename T >
void	shell_sort (std::vector< T > *arr)

Detailed Description

Sorting algorithms.

for io operations

for std::is_sorted

Sorting Algorithms.

for std::vector

for assert for typedef datatype uint64_t for IO operations

Sorting algorithms

for std::is_sorted, std::swap for assert for io operations

Sorting algorithms

Sorting algorithms

header files for collection of functions for a macro called assert which can be used to verify assumptions for io operations

Sorting algorithms

for assert for IO operations for std::vector for std::array

Sorting algorithms

Function Documentation

gnomeSort() [1/2]

template<typename T , size_t size>

std::array<T, size> sorting::gnomeSort

(

std::array< T, size >

arr

)

This implementation is for a C++-style array input. The function argument is a pass-by-value and hence a copy of the array gets created which is then modified by the function and returned.

Template Parameters

T	type of data variables in the array
size	size of the array

Parameters

[in]

arr

our array of elements.

Returns

array with elements sorted

                                                   {
    // few easy cases
    if (size <= 1) {
        return arr;
    }
 
    int index = 0;  // initialize loop index
    while (index < size) {
        // check for swap
        if ((index == 0) || (arr[index] >= arr[index - 1])) {
            index++;
        } else {
            std::swap(arr[index], arr[index - 1]);  // swap
            index--;
        }
    }
    return arr;
}

gnomeSort() [2/2]

template<typename T >

void sorting::gnomeSort	(	T *	arr,
		int	size
	)

This implementation is for a C-style array input that gets modified in place.

Parameters

[in,out]	arr	our array of elements.
	size	size of given array

                                 {
    // few easy cases
    if (size <= 1) {
        return;
    }
 
    int index = 0;  // initialize some variables.
    while (index < size) {
        // check for swap
        if ((index == 0) || (arr[index] >= arr[index - 1])) {
            index++;
        } else {
            std::swap(arr[index], arr[index - 1]);  // swap
            index--;
        }
    }
}

insertionSort() [1/2]

template<typename T >

void sorting::insertionSort

(

std::vector< T > *

arr

)

Insertion Sort Function

Template Parameters

T	type of array

Parameters

[in,out]

arr

pointer to array to be sorted

                                      {
    size_t n = arr->size();
 
    for (size_t i = 1; i < n; i++) {
        T temp = arr[0][i];
        int32_t j = i - 1;
        while (j >= 0 && temp < arr[0][j]) {
            arr[0][j + 1] = arr[0][j];
            j--;
        }
        arr[0][j + 1] = temp;
    }
}

Here is the call graph for this function:

insertionSort() [2/2]

template<typename T >

void sorting::insertionSort	(	T *	arr,
		int	n
	)

Insertion Sort Function.

Template Parameters

T	type of array

Parameters

[in,out]	arr	Array to be sorted
	n	Size of Array

                                  {
    for (int i = 1; i < n; i++) {
        T temp = arr[i];
        int j = i - 1;
        while (j >= 0 && temp < arr[j]) {
            arr[j + 1] = arr[j];
            j--;
        }
        arr[j + 1] = temp;
    }
}

merge()

template<class Iterator >

void sorting::merge	(	Iterator	l,
		Iterator	r,
		const Iterator	e,
		char	b[]
	)

merges 2 sorted adjacent segments into a larger sorted segment

best-case = worst-case = O(n)

Parameters

l	points to the left part
r	points to the right part, end of left part
e	points to end of right part
b	points at the buffer

                                                               {
    // create 2 pointers to point at the buffer
    auto p(reinterpret_cast<std::remove_reference_t<decltype(*l)>*>(b)), c(p);
    // move the left part of the segment
    for (Iterator t(l); r != t; ++t) *p++ = std::move(*t);
    // while neither the buffer nor the right part has been exhausted
    // move the smallest element of the two back to the container
    while (e != r && c != p) *l++ = std::move(*r < *c ? *r++ : *c++);
    // notice only one of the two following loops will be executed
    // while the right part hasn't bee exhausted, move it back
    while (e != r) *l++ = std::move(*r++);
    // while the buffer hasn't bee exhausted, move it back
    while (c != p) *l++ = std::move(*c++);
}

Here is the call graph for this function:

non_recursive_merge_sort() [1/3]

template<class Iterator >

void sorting::non_recursive_merge_sort	(	const Iterator	first,
		const Iterator	last
	)

bottom-up merge sort which sorts elements in a non-decreasing order

Parameters

first	points to the first element
last	points to 1-step past the last element

                                                                         {
    non_recursive_merge_sort(first, last, last - first);
}

Here is the call graph for this function:

non_recursive_merge_sort() [2/3]

template<class Iterator >

void sorting::non_recursive_merge_sort	(	const Iterator	first,
		const Iterator	last,
		const size_t	n
	)

bottom-up merge sort which sorts elements in a non-decreasing order

sorts elements non-recursively by breaking them into small segments, merging adjacent segments into larger sorted segments, then increasing the sizes of segments by factors of 2 and repeating the same process. best-case = worst-case = O(n log(n))

Parameters

first	points to the first element
last	points to 1-step past the last element
n	the number of elements

                                              {
    // create a buffer large enough to store all elements
    // dynamically allocated to comply with cpplint
    char* buffer = new char[n * sizeof(*first)];
    // buffer size can be optimized to largest power of 2 less than n
    // elements divide the container into equally-sized segments whose
    // length start at 1 and keeps increasing by factors of 2
    for (size_t length(1); length < n; length <<= 1) {
        // merge adjacent segments whose number is n / (length * 2)
        Iterator left(first);
        for (size_t counter(n / (length << 1)); counter; --counter) {
            Iterator right(left + length), end(right + length);
            merge(left, right, end, buffer);
            left = end;
        }
        // if the number of remaining elements (n * 2 % length) is longer
        // than a segment, merge the remaining elements
        if ((n & ((length << 1) - 1)) > length)
            merge(left, left + length, last, buffer);
    }
    delete[] buffer;
}

Here is the call graph for this function:

non_recursive_merge_sort() [3/3]

template<class Iterator >

void sorting::non_recursive_merge_sort	(	const Iterator	first,
		const size_t	n
	)

bottom-up merge sort which sorts elements in a non-decreasing order

Parameters

first	points to the first element
n	the number of elements

                                                                    {
    non_recursive_merge_sort(first, first + n, n);
}

Here is the call graph for this function:

partition()

int sorting::partition	(	int	arr[],
		int	low,
		int	high
	)

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 pivot = arr[high];  // taking the last element as pivot
    int i = (low - 1);      // Index of smaller element
 
    for (int j = low; j < high; j++) {
        // If current element is smaller than or
        // equal to pivot
        if (arr[j] <= pivot) {
            i++;  // increment index of smaller element
            int temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
        }
    }
    int temp = arr[i + 1];
    arr[i + 1] = arr[high];
    arr[high] = temp;
    return (i + 1);
}

pigeonSort()

template<std::size_t N>

std::array<int, N> sorting::pigeonSort

(

std::array< int, N >

arr

)

Pigeonhole sorting of array of size n The function will sort the array through Pigeonhole algorithm and print

Parameters

arr	unsorted array of elements

Returns

sorted array of elements

                                                  {
    // Finding min and max*
    auto min = std::min_element(std::begin(arr), std::end(arr));
    auto max = std::max_element(std::begin(arr), std::end(arr));
 
    // Range refers to the number of holes required
    int range = *max - *min + 1;
    int *hole = new int[range]();
 
    // Copying all array values to pigeonhole
    for (int i = 0; i < N; i++) {
        hole[arr[i] - *min] = arr[i];
    }
 
    // Deleting elements from list and storing to original array
    int count = 0;
    for (int i = 0; i < range; i++) {
        while (hole[i] != '\0') {
            arr[count] = hole[i];
            hole[i] = {};
            count++;
        }
    }
    delete[] hole;
 
    return arr;
}

Here is the call graph for this function:

quickSort()

void sorting::quickSort	(	int	arr[],
		int	low,
		int	high
	)

The main function that implements QuickSort arr[] --> Array to be sorted, low --> Starting index, high --> Ending index

                                             {
    if (low < high) {
        int p = partition(arr, low, high);
        quickSort(arr, low, p - 1);
        quickSort(arr, p + 1, high);
    }
}

Here is the call graph for this function:

quicksort() [1/2]

template<typename T >

void sorting::quicksort	(	std::vector< T > *	arr,
		int32_t	low,
		int32_t	high
	)

3-way partition based quick sort. This function accepts array pointer and modified the input array.

Template Parameters

T	type of data in the vector array

Parameters

[in,out]	arr	vector array to sort
[in]	low	lower limit of window to partition
[in]	high	upper limit of window to partition

                                                             {
    if (low >= high) {  // 1 or 0 elements
        return;
    }
 
    int32_t i = 0, j = 0;
 
    // i and j are passed as reference
    partition3(arr, low, high, &i, &j);
 
    // Recur two halves
    quicksort(arr, low, i);
    quicksort(arr, j, high);
}

quicksort() [2/2]

template<typename T >

std::vector<T> sorting::quicksort	(	std::vector< T >	arr,
		int32_t	low,
		int32_t	high
	)

3-way partition based quick sort. This function accepts array by value and creates a copy of it. The array copy gets sorted and returned by the function.

Template Parameters

T	type of data in the vector array

Parameters

[in]	arr	vector array to sort
[in]	low	lower limit of window to partition
[in]	high	upper limit of window to partition

Returns

sorted array vector

                                                                    {
    if (low >= high) {  // 1 or 0 elements
        return arr;
    }
 
    int32_t i = 0, j = 0;
 
    // i and j are passed as reference
    partition3(&arr, low, high, &i, &j);
 
    // Recur two halves
    quicksort(&arr, low, i);
    quicksort(&arr, j, high);
 
    return arr;
}

Here is the call graph for this function:

randomized_bogosort()

template<typename T , size_t N>

std::array<T, N> sorting::randomized_bogosort

(

std::array< T, N >

arr

)

Implement randomized Bogosort algorithm and sort the elements of a given array.

Template Parameters

T	typename of the array
N	length of array

Parameters

arr	array to sort

Returns

new array with elements sorted from a given array

                                                          {
    // Untill array is not sorted
    while (!std::is_sorted(arr.begin(), arr.end())) {
        std::random_shuffle(arr.begin(), arr.end());// Shuffle the array
    }
    return arr;
}

Here is the call graph for this function:

recursive_bubble_sort()

template<typename T >

void sorting::recursive_bubble_sort	(	std::vector< T > *	nums,
		uint64_t	n
	)

This is an implementation of the recursive_bubble_sort. A vector is passed to the function which is then dereferenced, so that the changes are reflected in the original vector. It also accepts a second parameter of type int and name n, which is the size of the array.

Template Parameters

T	type of data variables in the array

Parameters

nums	our array of elements.
n	size of the array

< base case; when size of the array is 1

< iterating over the entire array

< if a larger number appears before the smaller one, swap them.

                                                           {
    if (n == 1) {  //!< base case; when size of the array is 1
        return;
    }
 
    for (uint64_t i = 0; i < n - 1; i++) {  //!< iterating over the entire array
        //!< if a larger number appears before the smaller one, swap them.
        if ((*nums)[i] > (*nums)[i + 1]) {
            std::swap((*nums)[i], (*nums)[i + 1]);
        }
    }
 
    //!< calling the function after we have fixed the last element
    recursive_bubble_sort(nums, n - 1);
}

Here is the call graph for this function:

shell_sort() [1/3]

template<typename T >

void sorting::shell_sort

(

std::vector< T > *

arr

)

function overload - when input array is of type std::vector, simply send the data content and the data length to the above function.

                                   {
    shell_sort(arr->data(), arr->size());
}

Here is the call graph for this function:

shell_sort() [2/3]

template<typename T >

void sorting::shell_sort	(	T *	arr,
		size_t	LEN
	)

Optimized algorithm - takes half the time by utilizing Mar

                                    {
    const unsigned int gaps[] = {701, 301, 132, 57, 23, 10, 4, 1};
    const unsigned int gap_len = 8;
    size_t i, j, g;
 
    for (g = 0; g < gap_len; g++) {
        unsigned int gap = gaps[g];
        for (i = gap; i < LEN; i++) {
            T tmp = arr[i];
 
            for (j = i; j >= gap && (arr[j - gap] - tmp) > 0; j -= gap) {
                arr[j] = arr[j - gap];
            }
 
            arr[j] = tmp;
        }
    }
}

shell_sort() [3/3]

template<typename T , size_t N>

void sorting::shell_sort

(

T(&)

arr[N]

)

function overload - when input array is of a known length array type

                             {
    shell_sort(arr, N);
}

Here is the call graph for this function:

shuffle()

template<typename T , size_t N>

std::array<T, N> sorting::shuffle

(

std::array< T, N >

arr

)

Function to shuffle the elements of an array. (for reference)

Template Parameters

T	typename of the array
N	length of array

Parameters

arr	array to shuffle

Returns

new array with elements shuffled from a given array

                                              {
    for (int i = 0; i < N; i++) {
        // Swaps i'th  index with random index (less than array size)
        std::swap(arr[i], arr[std::rand() % N]);
    }
    return arr;
}

Here is the call graph for this function: