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  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. void print_prime_factors(long long int n)
  6. {
  7.   long long int i = 2;
  8.  
  9.   // print out the initial value of n
  10.  
  11.   cout << "n = " << n << endl;
  12.  
  13.   // keep dividing n by factors from smallest ones,
  14.   // until n becomes 1
  15.  
  16.   while (n>1)
  17.   {
  18.     // is n divisible by i?
  19.  
  20.     if (n%i == 0)
  21.     {
  22.       // if n divisible by i, divide it by i and print out i because
  23.       // it is a new prime factor (we must divide to not repeat
  24.       // the same factors but factor only what remains)
  25.  
  26.       n = n/i;
  27.  
  28.       cout << i << "    new value of n = " << n << endl;
  29.     }
  30.     else
  31.       i++;  // otherwise, we need to try divide by something bigger
  32.   }
  33. }
  34.  
  35. int main()
  36. {
  37.   long long int n;
  38.  
  39.   // read (long) integer n from input
  40.  
  41.   cin >> n;
  42.  
  43.   // compute and print out all prime factors
  44.  
  45.   print_prime_factors(n);
  46.  
  47.   // return 0 from main
  48.  
  49.   return 0;
  50. }
Success #stdin #stdout 0.02s 2684KB
comments (?)
stdin
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 100
stdout
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n = 100
2    new value of n = 50
2    new value of n = 25
5    new value of n = 5
5    new value of n = 1
https://ideone.com/5juYA
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
secret

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