The C language realization of narcissus number & primes & mass factor decomposition

Recently, I turned to the previous C language textbooks, saw three interesting small programs, including: Looking for "narcissus number", to determine whether a number is a prime, a number of qualitative factor decomposition. I want to put these three things in a program and write down this article.

Algorithm steps

1. Find the number of daffodils.

"Narcissus number" refers to a three-digit number whose numbers are cubic and equal to the number itself. For example: 153 is a "narcissus number", because the 153=1 three times the square +5 of the three +3 Times Square.

2. Determine if a number is prime.

A prime number is a method that can only be divisible by 1 and itself, judging whether a number is a prime: using this number to remove the square root of 2 to this number, if divisible, it indicates that this number is not a prime, and vice versa is prime.

3. The factorization of a number by a mass factor.

For the factorization of a number n, the first prime K (starting from the smallest 2) should be found, followed by the following steps:

(1) If the prime number is equal to n, then the process of decomposing the factorization has ended.

(2) If n is not equal to K, but n can be divisible by K, then the quotient of n divided by K is used as the new positive integer n, and the first step is repeated.

(3) If n cannot be divisible by K, the first step is repeated with k+1 as the new value of K.

This program flow

This procedure is divided into three steps: The first step, the search for "Narcissus number"; The second step is to determine whether the number of daffodils found is prime; the third step, if it is not prime, the number is decomposed by mass factor.

C Program code

Compile command

This program is compiled under Linux, the compiler command is: Gcc-g-o algorithmstudyalgorithmstudy.c–lm.

Note, do not ignore the "–LM", or compile will be an error, prompted to find "sqrt".

Program Run Results

After the compilation succeeds, execute the "algorithmstudy" command with the following results:

153 is a number of daffodils .

153 not Prime .

153=3*3*17

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370 is a number of daffodils .

370 not Prime .

370=2*5*37

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371 is a number of daffodils .

371 not Prime .

371=7*53

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407 is a number of daffodils .

407 not Prime .

407=11*37

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Narcissus & Prime number & C language implementation of mass factor decomposition