The C program realizes the prime number and the decomposition problem of integer _c language

This paper describes the C program to achieve the number of integers and decomposition problems, shared for everyone to reference. The specific methods are as follows:

Requirements: For a given integer, the output of all such prime numbers and decomposition, for the homogeneous decomposition of the output only once (for example, 5 has only one decomposition 2+3, and 3+2 is the 2+3 homogeneous decomposition).

For example:

For integer 8, you can use the following three types of decomposition:
(1) 8 = 2 + 2 + 2 + 2
(2) 8 = 2 + 3 + 3
(3) 8 = 3 + 5

When I saw this, my first reaction was to solve the knapsack problem.

Ideas are as follows:

F (N, array) = f (n-array[i], array), save the result, array is to save the value of the element, that is, all primes, refer to the previous question, if the prime number can only be used once, then set up a corresponding bool array can be marked as true every time you use, Then the recursive function needs to be reset to false, which is not necessary for the subject, but the array of saved results needs to be dropped from the prime number of the current attempt.

The code is as follows:

/* Copyright (c) alexingcool.  
All Rights Reserved. * #include <iostream> #include <iterator> #include <algorithm> #include <vector> using Namespac

e std;
vector<int> result;

Vector<int> Prvec;

 void Outputresult (int N, vector<int> &prime, vector<int> &result) {if (n < 0) return;
 if (N = = 0) {copy (Result.begin (), Result.end (), ostream_iterator<int> (cout, ""));
 cout << Endl;
 Return

 for (int i = 0; i < prime.size (); i++) {//To improve efficiency, you can make a judgment condition here as soon as possible to return if (N-prime[i] < 0) break;
 Result.push_back (Prime[i]);
 Outputresult (N-prime[i], Prime, result);
 Result.pop_back ();
 } void OutputResult2 (int n, vector<int> &prime, vector<int> &result, int position) {if (n < 0)

 Return
 if (N = = 0) {copy (Result.begin (), Result.end (), ostream_iterator<int> (cout, ""));
 cout << Endl;
 Return for (int i = position I < prime.size (); i++) {//To improve efficiency, you canThis makes a judgment condition and returns if (N-prime[i] < 0) break as soon as possible;
 Result.push_back (Prime[i]);
 OUTPUTRESULT2 (N-prime[i], prime, result, i);
 Result.pop_back ();
 BOOL IsPrime (int number) {if (number <= 1) return false;
 if (number = = 2) return true;
 for (int i = 2; i < number, i++) {if (number% i = = 0) return false;
return true; } void Generateprime (int number, vector<int> &result) {for (int i = 2; i < number-1; i++) {if IsPrime (i
 )) Result.push_back (i);
 } void Main () {int # = 8;
 Generateprime (number, Prvec);
 Outputresult (number, Prvec, result);
 cout << "Remove isomorphism" << Endl;
OUTPUTRESULT2 (number, Prvec, result, 0);

 }

The results of the operation are shown in the following illustration:

Note: For the isomorphism problem, I am looking at the output of the results, the Outputresult function, the result of 332, the result is not correct, an obvious feature is that after 3, the number of the following can not be less than 3, then only need to save 3 of the current position can be, Then, in the current position loop, the isomorphism problem can be eliminated.

It is believed that this article has certain reference value to everybody C program algorithm design learning.