sorting_algorithms.c

// Created by gunavaran on 3/9/21.

//Acknowledgement: The functions for all the sorting algorithms are extracted from
//https://www.geeksforgeeks.org/selection-sort/
//https://www.geeksforgeeks.org/insertion-sort/
//https://www.geeksforgeeks.org/bubble-sort/

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <sys/time.h>

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;
    }
}

void selectionSort(int arr[], int n) {
    int i, j, min_idx, temp;

    // 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
        temp = arr[min_idx];
        arr[min_idx] = arr[i];
        arr[i] = temp;
    }
}

void bubbleSort(int arr[], int n) {
    int i, j, temp;
    bool swapped;
    for (i = 0; i < n - 1; i++) {
        swapped = false;
        for (j = 0; j < n - i - 1; j++) {
            if (arr[j] > arr[j + 1]) {
                temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
                swapped = true;
            }
        }

        // IF no two elements were swapped by inner loop, then break
        if (swapped == false)
            break;
    }
}

// A utility function to print an array of size n
void printArray(int arr[], int n) {
    int i;
    for (i = 0; i < n; i++)
        printf("%d ", arr[i]);
    printf("\n");
}

int main() {
    int N = 100000, i, sorted_array[N], reversed_array[N], random_array[N];
    struct timeval start, end;
    long micros, seconds;

    for (i = 0; i < N; i++) {
        sorted_array[i] = i;
        reversed_array[N - 1 - i] = i;
        random_array[i] = rand() % N;

    }

//    printArray(sorted_array, N);
//    printArray(reversed_array, N);
//    printArray(random_array, N);

    gettimeofday(&start, NULL);
    insertionSort(sorted_array, N);
//    selectionSort(sorted_array, N);
//    bubbleSort(sorted_array, N);
    gettimeofday(&end, NULL);

    seconds = (end.tv_sec - start.tv_sec);
    micros = ((seconds * 1000000) + end.tv_usec) - (start.tv_usec);
    printf("Time elpased is %ld microseconds \n", micros);

    gettimeofday(&start, NULL);
    insertionSort(reversed_array, N);
//    selectionSort(reversed_array, N);
//    bubbleSort(reversed_array, N);
    gettimeofday(&end, NULL);

    seconds = (end.tv_sec - start.tv_sec);
    micros = ((seconds * 1000000) + end.tv_usec) - (start.tv_usec);
    printf("Time elpased is %ld microseconds \n", micros);

    gettimeofday(&start, NULL);
    insertionSort(random_array, N);
//    selectionSort(random_array, N);
//    bubbleSort(random_array, N);
    gettimeofday(&end, NULL);

    seconds = (end.tv_sec - start.tv_sec);
    micros = ((seconds * 1000000) + end.tv_usec) - (start.tv_usec);
    printf("Time elpased is %ld microseconds \n", micros);

//    printArray(sorted_array, N);
//    printArray(reversed_array, N);
//    printArray(random_array, N);

}