# Write a c program to find all perfect numbers

A number is said to be perfect if it equals the sum of its proper divisors. Alternatively, if the sum of a number's proper divisors exceeds the number itself, it is said to be abundant, while if the sum of a number's proper divisors is less than the number itself, it is said to be deficient. You should at your best on data-structures like an array, linked list, and string to clear any programming interview and believe me, you can not do this in one day or one week.

Sep 20,  · [Java] Printing perfect numbers from 1 to Mini Spy How would I write a program that prints every perfect number from 1 through , in Java, the most efficient way possible. This C Program checks whether a given number is perfect number. Perfect number is a number which is equal to sum of its divisor. For eg,divisors of 6 are 1,2 and 3. Find support in a large, thriving writing community. Upon completion of your certificate requirements, you must request your certificate by submitting a Certificate Request Form. Victoria College creative writing gothic genre a number of workshop-style courses that focus on writing poetry, short stories, and novels as part of its program.

It's rather a long process of learning through coding, and that's where these small coding problems help. Many of you might already heard about this question and some of you may already know the solution to this problem as well, but it's not enough to know just the answer.

In a programming interviewmany things matter apart from correct solution. For example, first thing Interviewer look is whether a candidate can ask right questions or not.

So before jumping straight to coding, spare a second or two to think about the problem and clear any doubt you may have. For example, you can ask following questions based upon problem statement given above: Does array contains only positive or negative numbers?

## Print Prime Number in C++

What if the same pair repeats twice, should we print it every time? Is reverse of pair is acceptable e. Do we need to print only distinct pair? How big the array is?

Many programmers afraid to ask questions instead they like to assume about it, but during coding interview IMHO it's always better to ask questions. First, it shows that you have not mugged the answer and second it demonstrates that you have the ability to think through a problem, which is a very important quality of any professional programmer.

Now let's go back to question, for simplicity we can assume that we just need to print a pair of integers once or twice depending upon their occurrence, but pair has to be distinct, 2,2 or 3, 3 is not valid pair. You take one number from array and then loop through array and output pairs which is equal to given sum.

You do this for all numbers in first array, as shown in following Java program: So let's dig deeper to improve this answer.

## C Program to Print all Perfect Numbers Between 1 to N

In order to find two numbers in an array whose sum equals a given value, we probably don't need compare each number with other. What we can do here is to store all numbers in a hashtable and just check if it contains second value in a pair.

For example, if given sum is 4 and one number in pair is 3, then other must be 1 or Do you remember the first question we asked, if array only contains positive numbers then we don't need to check for negative values in Map.

How is this solution better than previous one? It would require less comparisons. Only N to iterate through array and insert values in a Set because add and contains both O 1 operation in hash table.

So total complexity of solution would be O N. Here is a Java program which find the pair of values in the array whose sum is equal to k using Hashtable or Set. In this program we have also written a utility method to generate random numbers in a given range in Java.

You can use this method for testing with random inputs. By the way, random numbers are only good for demonstration, don't use them in your unit test. One more good thing you can learn from printPairsUsingSet method is pre validation, checking if inputs are valid to proceed further. By the this solution has few constraints, first it would need additional space of order O n to store numbers in Hashtable or Set, so you need additional space which could be problem if array is very large remember the question we asked before writing solution.

For a large array, you need a solution which doesn't require additional space, also known as in-place solution. If interviewer will ask you how do you find if two values in an array sum to a given value without any additional space, first solution will also not work because it's complexity is too high and it would too long to sort a large array.

A solution with complexity e. A more efficient in-place solution would be to sort the array and use two pointers to scan through array from both direction i. If sum of both the values are equal to given number then we output the pair and advance them. If the sum of two numbers is less than k then we increase the left pointer, else if the sum is greater than k we decrement the right pointer, until both pointers meet at some part of the array.There are many schemas for finding Prime numbers, and how to use them around the web.

This article is written to collect some of the most common techniques and explain how they work. I will take the definition for prime numbers from Clay Mathematics Institute, taken from the Millennium problem.

## C PROGRAM TO FIND PERFECT NUMBERS IN GIVEN RANGE

Write a program in the C programming language to find the factors or divisible of the inputted number. Make this program by using ' for loop ' Write a C program to print all the numbers upto the inputted number ; 0 people found this article useful This article was helpful.

Even and Odd Program in C++. In general Even numbers are those which are divisible by 2, and which numbers are not divisible 2 is called Odd number.. But in term of programming for find even number we check remainder of number is zero or not, If remainder is equal to zero that means number .

## C Program to check Perfect Square - Block Of Codes

Write a program that takes three integer command-line arguments a, b, and c and print the number of distinct values (1, 2, or 3) among a, b, and c. Write a program that takes five integer command-line arguments and prints the median (the third largest one).

There are many ways to write a C program to calculate the sum of two numbers i.e. using 3rd variable, using function, using pointers, etc.

But the simplest one is using a 3rd variable. The program is. Sep 25,  · factors of a number java program, java program to find factors of a number, java program to display factors of a number, prime factors of a number program in Skip navigation Sign in.

ProgrammingKnowledge: C Program to find the perfect numbers between a given range