mirror of https://github.com/TheAlgorithms/C
110 lines
2.4 KiB
C
110 lines
2.4 KiB
C
/**
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* @file
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* @author [Dhruv Pasricha](https://github.com/DhruvPasricha)
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* @brief [Selection Sort](https://en.wikipedia.org/wiki/Selection_sort)
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* implementation using recursion.
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*/
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#include <assert.h> /// for assert
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#include <stdio.h> /// for IO operations
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#include <stdlib.h> /// for dynamic memory allocation
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#include <time.h> /// for random numbers generation
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#include <inttypes.h> /// for uint8_t, int8_t
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/**
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* @brief Swapped two numbers using pointer
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* @param first pointer of first number
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* @param second pointer of second number
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*/
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void swap(int8_t *first, int8_t *second)
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{
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int8_t temp = *first;
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*first = *second;
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*second = temp;
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}
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/**
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* @brief Returns the index having minimum value using recursion
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* @param arr array to be sorted
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* @param size size of array
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* @return min_index index of an element having a minimum value
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*/
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uint8_t findIndex(const int8_t *arr, const uint8_t size)
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{
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if (size == 1)
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{
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return 0;
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}
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// marking recursive call to reach starting element
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uint8_t min_index = findIndex(arr, size - 1);
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if (arr[size - 1] < arr[min_index])
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{
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min_index = size - 1;
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}
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return min_index;
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}
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/**
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* @brief Selection Sort algorithm implemented using recursion
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* @param arr array to be sorted
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* @param size size of the array
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* @returns void
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*/
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void selectionSort(int8_t *arr, const uint8_t size)
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{
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if (size <= 1)
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{
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return;
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}
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/* findIndex(arr, size) returned the index having min value*/
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uint8_t min_index = findIndex(arr, size);
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/* arr[min_index] is the minimum value in the array*/
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if (min_index != 0)
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{
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swap(&arr[0], &arr[min_index]);
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}
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/*sorted the remaining array recursively*/
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selectionSort(arr + 1, size - 1);
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}
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/**
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* @brief Self-test implementations
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* @returns void
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*/
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static void test()
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{
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const uint8_t size = 10;
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int8_t *arr = (int8_t *)calloc(size, sizeof(int8_t));
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/* generate size random numbers from 0 to 100 */
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for (uint8_t i = 0; i < size; i++)
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{
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arr[i] = rand() % 100;
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}
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selectionSort(arr, size);
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for (uint8_t i = 0; i < size - 1; ++i)
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{
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assert(arr[i] <= arr[i + 1]);
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}
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free(arr);
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}
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/**
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* @brief Main function
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* @returns 0 on exit
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*/
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int main()
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{
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/* Intializes random number generator */
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srand(time(NULL));
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test(); // run self-test implementations
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return 0;
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}
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