# fastest search algorithm for sorted array

Sorting Algorithms. That's very interesting but you need to give more information. However, I never know which is the fastest (for a random array of integers). Gaussian? If the search ends with the remaining half being empty, the target is not in the array. https://en.wikipedia.org/wiki/Sorting_algorithm, MAINTENANCE WARNING: Possible downtime early morning Dec 2/4/9 UTC (8:30PM…, “Question closed” notifications experiment results and graduation. You can find the formal proof for sorting complexity lower bound here: The fastest integer sorting algorithm in terms of worst-case I have come across is the one by Andersson et al. 1) Get the Middle of the array and make it root. An insertion sort is a simple sort which is most effective on small lists. But realistically, in practice, the sorting algorithm is rarely a major performance bottleneck. Merge sort is fast in the case of a linked list. @gen Take a look at Radix sort. It only takes a minute to sign up. $\Omega(n \log n)$ is not a universal lower bound for sorting. The idea of an insertion sort … Examples of back of envelope calculations leading to good intuition? This is an unbreakable bound. Line Clipping | Set 1 (Cohen–Sutherland Algorithm), MO's Algorithm (Query Square Root Decomposition) | Set 1 (Introduction), Know Your Sorting Algorithm | Set 1 (Sorting Weapons used by Programming Languages), Know Your Sorting Algorithm | Set 2 (Introsort- C++’s Sorting Weapon), Sorting objects using In-Place sorting algorithm. I got my money returned for a product that I did not return. @Evil Yes. However, I was a bit curious on which other sorting approaches (not comparison-based) you were referring to; Radix Sort is exactly the kind of O(n) algorithm I was talking about - you have to 'assume' something about the input (fixed-width integers). So my questions are: In general terms, there are the $O(n^2)$ sorting algorithms, such as insertion sort, bubble sort, and selection sort, which you should typically use only in special circumstances; Quicksort, which is worst-case $O(n^2)$ but quite often $O(n\log n)$ with good constants and properties and which can be used as a general-purpose sorting procedure; the $O(n\log n)$ algorithms, like merge-sort and heap-sort, which are also good general-purpose sorting algorithms; and the $O(n)$, or linear, sorting algorithms for lists of integers, such as radix, bucket and counting sorts, which may be suitable depending on the nature of the integers in your lists. This is unbeatable. That's true, of course. Theoretically, is it possible that there are even faster ones? In this sense, it is not a general-purpose sorting algorithm, right? Given an array $A$ with $n$ integer elements, you need exactly $(n-1)$ comparisons between elements in order to check if $A$ is sorted (just start at the beginning of the array and check the next element against the last element). comparisons needed, and as few as N-1)". But if the list is unsorted to a large extend then this algorithm holds good for small datasets or lists. A sorting algorithm that slightly improves on selection sort, Print a case where the given sorting algorithm fails, Sorting Algorithm Visualization : Merge Sort, Sorting Algorithm Visualization : Quick Sort, Sorting algorithm visualization : Insertion Sort, Sorting algorithm visualization : Heap Sort, Find the Minimum length Unsorted Subarray, sorting which makes the complete array sorted, Lower bound for comparison based sorting algorithms, Sorting 2D Vector in C++ | Set 2 (In descending order by row and column), Sleep Sort – The King of Laziness / Sorting while Sleeping, Sorting Vector of Pairs in C++ | Set 1 (Sort by first and second), Check if the Left View of the given tree is sorted or not, new vs malloc() and free() vs delete in C++, Minimum steps to reach target by a Knight | Set 2, Difference between NP hard and NP complete problem. All sorting algorithms based on comparing elements, such as quicksort and merge sort, require at least (⁡) comparisons in the worst case. A sorting algorithm is an algorithm that makes arrange in a certain order. I suppose the lower bound is probably better rendered $\Omega$. Theoretical lower bound of finding number of occurrences of a target integer in a sorted array. In theory Quicksort is in fact $\mathcal O(n^2)$. Random with what distribution? Following is a simple algorithm where we first find the middle node of list and make it root of the tree to be constructed. If you allow other operations than comparisons, the trivial bound $\Omega(n)$ holds (and can be reached in special cases), as you have to read all the keys. The fundamental task is to put the items in the desired order so that the records are re-arranged for making searching easier. Quicksort isn't well suited for parallel processing. Additionally, if you are not familiar with what $\Omega(n)$ or $O(n)$: Both notations mean that the algorithm takes approximately $n$ operations to complete (could be $2n$ or $3n-5$, but not $1$ or $n^2$ operations). Writing code in comment? Insertion sort is a simple sorting algorithm that builds the final sorted array (or list) one item at a time. Other answers considered extraneous ideas about random distributions and space complexity which are probably out of the scope for high school studies. What does "random array of integers" mean? Which sorting algorithm makes minimum number of memory writes? Fastest in-place sorting algorithm for Epochtime. Only if you find that (i) sorting is a large fraction of the overall running time, and (ii) the running time is unacceptable, should you bother messing around with the sorting algorithm. A Sorting Algorithm is used to rearrange a given array or list elements according to a comparison operator on the elements. acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Data Structures and Algorithms Online Courses : Free and Paid, Recursive Practice Problems with Solutions, Converting Roman Numerals to Decimal lying between 1 to 3999, Commonly Asked Algorithm Interview Questions | Set 1, Generate all permutation of a set in Python, Comparison among Bubble Sort, Selection Sort and Insertion Sort, DDA Line generation Algorithm in Computer Graphics. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. If you only allow making decisions by means of comparison of the keys, it is well-known that at least $\log(n! Old Budrys(?) Quick Sort in is an in-place sort (i.e. How can one become good at Data structures and Algorithms easily? @Raphael Meh. The array has fewer than 64 elements in it. Correct implementation has O(n) complexity for Int32 for example. However, insertion sort provides several advantages: Python's built-in sort() has used this algorithm for some time, apparently with good results. Anything asymptotically faster than that has to make assumptions about the data: for example, radix sort runs in linear time assuming that every element of the array is at most some constant. The answer, as is often the case for such questions, is "it depends". However, if your array is sorted there is a much faster algorithm you can employ to determine whether or not a particular element exists within the array, known as the binary search algorithm. Since all sorting algorithms are bound below by$\Omega(n)\$, I would argue that both radix sort and bucket sort are the fastest algorithms for sorting an array of integers.