The number of daffodils & amp; prime number & amp; the C language implementation of prime factor decomposition, the number of daffodils vb

The C language implementation of daffodils & prime numbers & prime factor decomposition, and daffodils vb

Recently, I flipped through the C language textbooks and read three interesting small programs, including: search for "Daffodils", judge whether a number is a prime number, and perform prime factor decomposition on a number. I want to put these three items in a program and write this article.

 

Algorithm steps

1. Search for "Daffodils ".

The "Daffodils" refers to a three-digit number. The cubes of each digit are equal to the number itself. For example, 153 is a "Daffodils" because 153 = the power of 1 + the power of 5 + the power of 3.

 

2. Determine whether a number is a prime number.

Prime Number refers to the number that can only be divided by 1 and itself. To determine whether a number is a prime number, use this number to divide it by the square root of the number. If it can be divisible, it indicates that this number is not a prime number, and vice versa.

 

3. Perform prime factor decomposition on a number.

For a prime factor decomposition of a number n, you should first find a prime number k (starting from 2), and then follow the steps below:

(1) If the prime number is equal to n, the process of decomposing the prime factor is over.

(2) If n is not equal to k, but n can be divisible by k, 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, k + 1 is used as the new value of k and the first step is repeated.

 

Procedures

This program takes three steps: the first step is to find the "Daffodils"; the second step is to judge whether the "Daffodils" is a prime number; the third step, if it is not a prime number, this number is decomposed by a prime factor.

 

C program code

Compile command

This program is compiled in Linux with the command gcc-g-o AlgorithmStudyAlgorithmStudy. c-lm.

Note: Do not ignore "-lm". Otherwise, an error will be reported during compilation, prompting that "sqrt" cannot be found ".

 

Program running result

After the compilation is successful, run the "AlgorithmStudy" command. The result is as follows:

153 is the number of daffodils.

153 is not a prime number.

153 = 3*3*17

------

370 is the number of daffodils.

370 is not a prime number.

370 = 2*5*37

------

371 is the number of daffodils.

371 is not a prime number.

371 = 7*53

------

407 is the number of daffodils.

407 is not a prime number.

407 = 11*37

------

 

 

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