Sorting Algorithms

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Practice Problems on Sorting
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What is Sorting?

A Sorting Algorithm is used to rearrange a given array or list of elements according to a comparison operator on the elements. The comparison operator is used to decide the new order of elements in the respective data structure.

For Example: The below list of characters is sorted in increasing order of their ASCII values. That is, the character with a lesser ASCII value will be placed first than the character with a higher ASCII value.

Sorting Algorithms

Sorting Algorithms:

Table of Complexity Comparison:

Name	Best Case	Average Case	Worst Case	Memory	Stable	Method Used
Quick Sort					No	Partitioning
Merge Sort				n	Yes	Merging
Heap Sort				1	No	Selection
Insertion Sort	n			1	Yes	Insertion
Tim Sort	n			n	Yes	Insertion & Merging
Selection Sort				1	No	Selection
Shell Sort				1	No	Insertion
Bubble Sort	n			1	Yes	Exchanging
Tree Sort				n	Yes	Insertion
Cycle Sort				1	No	Selection
Strand Sort	n			n	Yes	Selection
Cocktail Shaker Sort	n			1	Yes	Exchanging
Comb Sort				1	No	Exchanging
Gnome Sort	n			1	Yes	Exchanging
Odd–even Sort	n			1	Yes	Exchanging

Library Implementations:

1. Introsort – C++’s Sorting Weapon
2. Comparator function of qsort() in C
3. sort() in C++ STL
4. C qsort() vs C++ sort()
5. Arrays.sort() in Java with examples
6. Collections.sort() in Java with Examples

Some standard problems on Sorting:

• Easy:
  1. Sort elements by frequency
  2. Sort an array of 0s, 1s and 2s
  3. Sort numbers stored on different machines
  4. Sort an array in wave form
  5. Check if any two intervals overlap among a given set of intervals
  6. How to sort an array of dates in C/C++?
  7. Sorting Strings using Bubble Sort
  8. Find missing elements of a range
  9. Sort an array according to count of set bits
  10. Sort even-placed elements in increasing and odd-placed in decreasing order
  11. Sort an array when two halves are sorted
  12. Sorting Big Integers
  13. Sort a linked list of 0s, 1s and 2s
• Medium:
  1. Inversion count in Array using Merge Sort
  2. Find the Minimum length Unsorted Subarray, sorting which makes the complete array sorted
  3. Sort a nearly sorted (or K sorted) array
  4. Sort n numbers in range from 0 to n^2 – 1 in linear time
  5. Sort an array according to the order defined by another array
  6. Find the point where maximum intervals overlap
  7. Find a permutation that causes worst case of Merge Sort
  8. Sort Vector of Pairs in ascending order in C++
  9. Minimum swaps to make two arrays identical
  10. Chocolate Distribution Problem
  11. Permute two arrays such that sum of every pair is greater or equal to K
  12. Bucket Sort To Sort an Array with Negative Numbers
  13. Sort a Matrix in all way increasing order
  14. Convert an Array to reduced form using Vector of pairs
  15. Smallest Difference Triplet from Three arrays
  16. Check if it is possible to sort an array with conditional swapping of adjacent allowed
• Hard:
  1. Find Surpasser Count of each element in array
  2. Count distinct occurrences as a subsequence
  3. Count minimum number of subsets (or subsequences) with consecutive numbers
  4. Chose k array elements such that difference of maximum and minimum is minimized
  5. Minimum swap required to convert binary tree to binary search tree
  6. K-th smallest element after removing some integers from natural numbers
  7. Maximum difference between frequency of two elements such that element having greater frequency is also greater
  8. Minimum swaps to reach permuted array with at most 2 positions left swaps allowed
  9. Find whether it is possible to make array elements same using one external number
  10. Sort an array after applying the given equation
  11. Print array of strings in sorted order without copying one string into another

Quick Links :

1. ‘Practice Problems’ on Sorting
2. ‘Quizzes’ on Sorting

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• Learn Data Structure and Algorithms | DSA Tutorial

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