Why is it faster to process a sorted array than an unsorted array?

Answer 1

With a sorted array we have knowledge of certain information about the data set, such as the maximum being at the front or end of the array, if it is descending or ascending respectively. This is the same with the minimum as it will be the opposite from the maximum.

Now if we had to find the range of this array, largest - smallest, it only takes us two operations to do so, i.e first minus last or last minus first.

In an unsorted array we have no idea where the largest and smallest element is. For example finding the range would require us to loop through the entire array to find both the largest and smallest.

Going into some basic time complexity this takes us N amount of operations, as we had to loop through the entire array. Compared to only two operations it is much faster (if the data set had 1 million items in it, it makes a big difference).

With this understanding you can move into advanced topics such as Binary Search, which only works on a sorted list and topics such as Pre-Sorting which is an algorithm development strategy.

Answer 2

It is like what @Greg stated.
In a nutshell, it would just be like:
Telling a guy to search the letter A from a disorganized list of alphabets
VS
Telling a guy to search the letter A from an organized list of alphabets

Answer 3

because there is no time taken for sorting the array in sorted array.but in unsorted array it will be sort first and then process it

Answer 4

it might not be faster. depends on what you wanna do . if you want to add 3 to each element then it can be sorted or not, you still need to go trough each element in turn

Answer 5

You can also formulate better algorithms to manipulate your array when it is sorted :)

Answer 6

take a real world example

if a give you a list of all countries in the world then I told you find you the country like India.

I will give you 2 list
list 1 will be in sorted order
list 2 will be in unsorted order

which one will be your fastest way to find the country?

Answer 7

what shall i do to learn C++