Timsort in C++

Yasin Cakal

Timsort is an efficient sorting algorithm that was developed by Tim Peters in 2002. It is an algorithm that is used for sorting arrays of data. It is based on merge sort and insertion sort, which are two of the most commonly used algorithms for sorting data. Timsort is designed to be efficient in both time and space complexity, making it a great choice for sorting data. In this article, we will discuss how the Timsort algorithm works, its time complexity, and its space complexity. We will also provide examples of code written in C++ to illustrate the different aspects of the algorithm.

How Timsort Works

Timsort is an adaptive sorting algorithm that is designed to be efficient in sorting data. It works by dividing the data into two parts: the sorted part and the unsorted part. The algorithm starts by finding the smallest element in the unsorted part and placing it at the beginning of the sorted part. It then looks for the next smallest element and places it right after the first one. This process continues until all the elements in the unsorted part have been placed in the sorted part.

Once the elements in the unsorted part have been placed in the sorted part, the algorithm then moves on to the next step, which is merging the sorted parts. This is done by taking two or more sorted parts and merging them into one larger sorted part. This process is repeated until the entire array is sorted.

Time Complexity

The time complexity of Timsort is a function of the size of the data being sorted. The best case scenario for Timsort is when the data is already sorted. In this case, the algorithm only needs to perform one pass over the data to sort it, resulting in a time complexity of O(n) (where n is the size of the data).

The worst case scenario for Timsort is when the data is completely unsorted. In this case, the algorithm needs to perform multiple passes over the data to sort it, resulting in a time complexity of O(n log n).

The average case time complexity of Timsort is also O(n log n). This is because the algorithm is designed to be adaptive and will use the best sorting technique for the data being sorted.

Space Complexity

The space complexity of Timsort is O(n). This means that the algorithm requires a constant amount of extra space in order to sort the data. This is because the algorithm does not create any additional data structures or require any extra memory to store data.

Example of Timsort in C++

Below is an example of the Timsort algorithm written in C++. This example implements the algorithm using an array of integers.

#include <iostream> 

using namespace std; 

void timSort(int arr[], int n) 
{ 
    // Find the smallest element and place it at the beginning of the array 
    int minimum = arr[0]; 
    int index = 0; 
    for(int i=0; i<n; i++) 
    { 
        if(arr[i] < minimum) 
        { 
            minimum = arr[i]; 
            index = i; 
        } 
    } 
    arr[index] = arr[0]; 
    arr[0] = minimum; 
  
    // Merge the sorted and unsorted parts 
    int mid = 1; 
    for(int i=1; i<n; i++) 
    { 
        int j = i; 
  
        // Move elements of sorted part one step ahead 
        while(j >= mid && arr[j] < arr[j-mid]) 
        { 
            int temp = arr[j]; 
            arr[j] = arr[j-mid]; 
            arr[j-mid] = temp; 
            j--; 
        } 
  
        // Update the size of sorted part 
        if(i == 2*mid-1) 
            mid = 2*mid; 
    } 
} 

// Driver function 
int main() 
{ 
    int arr[] = {5, 4, 3, 2, 1}; 
    int n = sizeof(arr)/sizeof(arr[0]); 
  
    timSort(arr, n); 
  
    for(int i=0; i<n; i++) 
        cout << arr[i] << " "; 
  
    return 0; 
}

Conclusion

In this article, we discussed the Timsort algorithm and how it works. We also looked at the time and space complexity of the algorithm, as well as an example of the algorithm written in C++. Timsort is an efficient algorithm for sorting data and is a great choice for sorting large amounts of data.

Exercises

Write a C++ program that takes in an array of integers and sorts them using Timsort.

#include <iostream> 

using namespace std; 

void timSort(int arr[], int n) 
{ 
    // Find the smallest element and place it at the beginning of the array 
    int minimum = arr[0]; 
    int index = 0; 
    for(int i=0; i<n; i++) 
    { 
        if(arr[i] < minimum) 
        { 
            minimum = arr[i]; 
            index = i; 
        } 
    } 
    arr[index] = arr[0]; 
    arr[0] = minimum; 
  
    // Merge the sorted and unsorted parts 
    int mid = 1; 
    for(int i=1; i<n; i++) 
    { 
        int j = i; 
  
        // Move elements of sorted part one step ahead 
        while(j >= mid && arr[j] < arr[j-mid]) 
        { 
            int temp = arr[j]; 
            arr[j] = arr[j-mid]; 
            arr[j-mid] = temp; 
            j--; 
        } 
  
        // Update the size of sorted part 
        if(i == 2*mid-1) 
            mid = 2*mid; 
    } 
} 

// Driver function 
int main() 
{ 
    int arr[] = {5, 4, 3, 2, 1}; 
    int n = sizeof(arr)/sizeof(arr[0]); 
  
    timSort(arr, n); 
  
    for(int i=0; i<n; i++) 
        cout << arr[i] << " "; 
  
    return 0; 
}

Write a C++ program that takes in an array of integers and uses Timsort to find the minimum element in the array.

#include <iostream> 

using namespace std; 

int findMinimum(int arr[], int n) 
{ 
    // Find the smallest element and place it at the beginning of the array 
    int minimum = arr[0]; 
    int index = 0; 
    for(int i=0; i<n; i++) 
    { 
        if(arr[i] < minimum) 
        { 
            minimum = arr[i]; 
            index = i; 
        } 
    } 
    return minimum; 
} 

// Driver function 
int main() 
{ 
    int arr[] = {5, 4, 3, 2, 1}; 
    int n = sizeof(arr)/sizeof(arr[0]); 
  
    int minimum = findMinimum(arr, n); 
  
    cout << "The minimum element in the array is: " << minimum; 
  
    return 0; 
}

Write a C++ program that takes in an array of integers and uses Timsort to find the maximum element in the array.

#include <iostream> 

using namespace std; 

int findMaximum(int arr[], int n) 
{ 
    // Find the largest element and place it at the beginning of the array 
    int maximum = arr[0]; 
    int index = 0; 
    for(int i=0; i<n; i++) 
    { 
        if(arr[i] > maximum) 
        { 
            maximum = arr[i]; 
            index = i; 
        } 
    } 
    return maximum; 
} 

// Driver function 
int main() 
{ 
    int arr[] = {5, 4, 3, 2, 1}; 
    int n = sizeof(arr)/sizeof(arr[0]); 
  
    int maximum = findMaximum(arr, n); 
  
    cout << "The maximum element in the array is: " << maximum; 
  
    return 0; 
}

Write a C++ program that takes in an array of strings and uses Timsort to sort the strings in alphabetical order.

#include <iostream> 
#include <string> 

using namespace std; 

void timSort(string arr[], int n) 
{ 
    // Find the smallest element and place it at the beginning of the array 
    string minimum = arr[0]; 
    int index = 0; 
    for(int i=0; i<n; i++) 
    { 
        if(arr[i] < minimum) 
        { 
            minimum = arr[i]; 
            index = i; 
        } 
    } 
    arr[index] = arr[0]; 
    arr[0] = minimum; 
  
    // Merge the sorted and unsorted parts 
    int mid = 1; 
    for(int i=1; i<n; i++) 
    { 
        int j = i; 
  
        // Move elements of sorted part one step ahead 
        while(j >= mid && arr[j] < arr[j-mid]) 
        { 
            string temp = arr[j]; 
            arr[j] = arr[j-mid]; 
            arr[j-mid] = temp; 
            j--; 
        } 
  
        // Update the size of sorted part 
        if(i == 2*mid-1) 
            mid = 2*mid; 
    } 
} 

// Driver function 
int main() 
{ 
    string arr[] = {"apple", "banana", "cherry", "date"}; 
    int n = sizeof(arr)/sizeof(arr[0]); 
  
    timSort(arr, n); 
  
    for(int i=0; i<n; i++) 
        cout << arr[i] << " "; 
  
    return 0; 
}

Write a C++ program that takes in an array of integers and uses Timsort to sort the array in descending order.

#include <iostream> 

using namespace std; 

void timSortDescending(int arr[], int n) 
{ 
    // Find the largest element and place it at the beginning of the array 
    int maximum = arr[0]; 
    int index = 0; 
    for(int i=0; i<n; i++) 
    { 
        if(arr[i] > maximum) 
        { 
            maximum = arr[i]; 
            index = i; 
        } 
    } 
    arr[index] = arr[0]; 
    arr[0] = maximum; 
  
    // Merge the sorted and unsorted parts 
    int mid = 1; 
    for(int i=1; i<n; i++) 
    { 
        int j = i; 
  
        // Move elements of sorted part one step ahead 
        while(j >= mid && arr[j] > arr[j-mid]) 
        { 
            int temp = arr[j]; 
            arr[j] = arr[j-mid]; 
            arr[j-mid] = temp; 
            j--; 
        } 
  
        // Update the size of sorted part 
        if(i == 2*mid-1) 
            mid = 2*mid; 
    } 
} 

// Driver function 
int main() 
{ 
    int arr[] = {5, 4, 3, 2, 1}; 
    int n = sizeof(arr)/sizeof(arr[0]); 
  
    timSortDescending(arr, n); 
  
    for(int i=0; i<n; i++) 
        cout << arr[i] << " "; 
  
    return 0; 
}

Data Structures and Algorithms with C++

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