# How does merge sort work in java ## How does merge sort work?

Merge sort is one of the most efficient sorting algorithms. It works on the principle of Divide and Conquer. Merge sort repeatedly breaks down a list into several sublists until each sublist consists of a single element and merging those sublists in a manner that results into a sorted list.

## How do you perform a merge sort in Java?

The algorithm can be described as the following 2 step process:

1. Divide: In this step, we divide the input array into 2 halves, the pivot being the midpoint of the array. …
2. Conquer: In this step, we sort and merge the divided arrays from bottom to top and get the sorted array.

## Where is merge sort used?

Mergesort is used when we want a guaranteed running time of O ( n log ⁡ n ) O(n log n) O(nlogn), regardless of the state of the input. Mergesort is a stable sort with a space complexity of O ( n ) O(n) O(n).

Quicksort

## How do you solve merge sort?

Here’s how merge sort uses divide-and-conquer:

1. Divide by finding the number q of the position midway between p and r. …
2. Conquer by recursively sorting the subarrays in each of the two subproblems created by the divide step. …
3. Combine by merging the two sorted subarrays back into the single sorted subarray array[p..

## What is merge sort with example?

An example of merge sort. First divide the list into the smallest unit (1 element), then compare each element with the adjacent list to sort and merge the two adjacent lists. … In computer science, merge sort (also commonly spelled mergesort) is an efficient, general-purpose, comparison-based sorting algorithm.

## What is true for merge sort?

MergeSort is a Divide and Conquer algorithm. It divides input array in two halves, calls itself for the two halves and then merges the two sorted halves. The merg() function is used for merging two halves.

n*log(n)

## Why is merge sort best?

Efficiency : Merge sort is more efficient and works faster than quick sort in case of larger array size or datasets. Quick sort is more efficient and works faster than merge sort in case of smaller array size or datasets.

## Why is QuickSort better than mergesort?

Auxiliary Space : Mergesort uses extra space, quicksort requires little space and exhibits good cache locality. … Locality of reference : Quicksort in particular exhibits good cache locality and this makes it faster than merge sort in many cases like in virtual memory environment.

## Is insertion sort a stable algorithm?

A sorting algorithm is said to be stable if two objects with equal keys appear in the same order in sorted output as they appear in the input unsorted array. Some sorting algorithms are stable by nature like Insertion sort, Merge Sort, Bubble Sort, etc. … In this case, unstable sort generates problems.6 мая 2017 г.

## Is quicksort greedy algorithm?

quicksort recursively divides its input into subsequences on either side of an arbitrarily chosen pivot, optimizing the division to maximize sortedness at each stage.

## How do you calculate time complexity?

The time complexity, measured in the number of comparisons, then becomes T(n) = n – 1. In general, an elementary operation must have two properties: There can’t be any other operations that are performed more frequently as the size of the input grows.