# What is the time complexity of external sort?

## What is the time complexity of external sort?

Like in-memory sorts, efficient external sorts require O(n log n) time: linear increases in data size require logarithmic increases in the number of passes, and each pass takes a linear number of reads and writes.

## How merge sort is used in external sorting?

External sorting typically uses a hybrid sort-merge strategy. In the sorting phase, chunks of data small enough to fit in main memory are read, sorted, and written out to a temporary file. In the merge phase, the sorted sub-files are combined into a single larger file.

How do you calculate external merge sort?

Estimating cost for External Sort-Merge Method It takes a total of 2br block transfers. Initially, the value of the number of runs is [br/M]. As the number of runs decreases by M-1 in each merge pass, so it needs a total number of [log M-1(br/M)] merge passes.

What is external sort and merge algorithm?

The external merge sort is a technique in which the data is stored in intermediate files and then each intermediate files are sorted independently and then combined or merged to get a sorted data. For example: Let us consider there are 10,000 records which have to be sorted.

### What is the basic algorithm used for external sorting?

[3] provided a lot of basic knowledge of sorting algorithm, including the replacement selection and merge sort. Merge sort is the algorithm most commonly used for external sorting. External merge sorting is generally divided into two phases: run formation phase (see figure 1) and run merge phase (see figure 2).

### What is external sort explain radix sort using an example?

Radix sort is one of the sorting algorithms used to sort a list of integer numbers in order. In radix sort algorithm, a list of integer numbers will be sorted based on the digits of individual numbers. For example, if the largest number is a 3 digit number then that list is sorted with 3 passes.

What is best case time complexity of merge sort?

Sorting algorithms

Algorithm Data structure Time complexity:Best
Merge sort Array O(n log(n))
Heap sort Array O(n log(n))
Smooth sort Array O(n)
Bubble sort Array O(n)

What is the best case and worst case complexity of selection sort?

Time and Space Complexity Comparison Table :

Sorting Algorithm Time Complexity Space Complexity
Best Case Worst Case
Selection Sort Ω(N2) O(1)
Insertion Sort Ω(N) O(1)
Merge Sort Ω(N log N) O(N)

## What are the two phases of external sorting?

External Sorting with Example in C++ In also possess two phases like in merge sort, In the sort phase, small memory size data sets are sorted and then in merge phase, these are combined to a single dataset. For a huge data set which cannot be processed in a single go. Data is divided into small chunks.

## What is the space complexity of the merge sort algorithm?

The space complexity of merge sort algorithm is Θ (n). if we are not concerned with auxiliary space used. Assume that a merge sort algorithm in the worst case takes 30 seconds for an input of size 64. Which of the following most closely approximates the maximum input size of a problem that can be solved in 6 minutes?

What is the recurrence relation for time complexity of merge sort?

If T (n) is the time required by merge sort for sorting an array of size n, then the recurrence relation for time complexity of merge sort is- On solving this recurrence relation, we get T (n) = Θ (nlogn). Thus, time complexity of merge sort algorithm is T (n) = Θ (nlogn).

What is the time complexity of merge sort in Python?

Time taken for merge sort is O (nlogn), but there are at most run_size elements. So the time complexity is O (run_size log run_size) and then to merge the sorted arrays the time complexity is O (n). Therefore, the overall time complexity is O (n + run_size log run_size).

### What is the merge phase of External sorting?

In the merge phase, the sorted sub-files are combined into a single larger file. One example of external sorting is the external merge sort algorithm, which sorts chunks that each fit in RAM, then merges the sorted chunks together. We first divide the file into runs such that the size of a run is small enough to fit into main memory.