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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. typedef long long ll;
  4.  
  5. vector<ll> v;
  6.  
  7. ll power(ll a, ll n,ll m){
  8.  
  9. 	if(n==0)
  10. 	  return 1;
  11.  
  12. 	  if(n%2==0){
  13. 	     return	power((a%m*a%m)%m,n/2,m);
  14. 	  }
  15.  
  16. 	 return (a%m*power((a%m*a%m)%m,n/2,m))%m;
  17.  
  18.  
  19.  
  20.  
  21.  
  22. }
  23.  
  24. ll modInverse(ll a, ll m)
  25. {
  26.     ll m0 = m;
  27.     ll y = 0, x = 1;
  28.  
  29.     if (m == 1)
  30.       return 0;
  31.  
  32.     while (a > 1)
  33.     {
  34.  
  35.         ll q = a / m;
  36.         ll t = m;
  37.  
  38.  
  39.         m = a % m, a = t;
  40.         t = y;
  41.  
  42.  
  43.         y = x - q * y;
  44.         x = t;
  45.     }
  46.  
  47.  
  48.     if (x < 0)
  49.        x += m0;
  50.  
  51.     return x;
  52. }
  53.  
  54.  
  55. int main() {
  56. 	int* b=new int[100010];
  57.     for(int i=0;i<100010;i++){
  58.     	b[i]=1;
  59.     }
  60.     b[0]=0;
  61.     b[1]=0;
  62.     for(int i=2;i<1000;i++){
  63.     	for(int j=i*i;j<100010;j+=i){
  64.     		b[j]=0;
  65.     	}
  66.     }
  67.  
  68. 	 for(int i=0;i<100010;i++){
  69.     	if(b[i]==1)
  70.     	  v.push_back(i);
  71.     }
  72.   srand (time(NULL));	
  73.   ll prime1 = v[(rand() % v.size())];
  74.   ll prime2 = v[(rand() % v.size())];
  75.   ll prime = prime1*prime2;
  76.   ll euler =((prime1-1)*(prime2-1));
  77.   ll p=v.size();
  78.   ll index;
  79.   while(1){
  80.         index = rand() % p;
  81.        if(v[index]<euler)
  82.         break;
  83.  
  84.         else
  85.           p=index;
  86. }
  87.   ll encry= v[index];
  88.   ll decry =modInverse(encry, euler);
  89.   cout<<decry<<endl;
  90.   string s;
  91.   getline(cin,s);
  92.   for(int i=0;i<s.length();i++){
  93.   	int p =int(s[i]-'a');
  94.   	ll j=power(p,encry,prime);
  95.   	ll l=power(j,decry,prime);
  96.  
  97.  
  98.   	cout<<p<<"  " <<j<<"   "<<char(j)<<"   "<<l<<endl;
  99.  
  100.   }
  101.  
  102.  
  103.  
  104. }
Success #stdin #stdout 0s 4184KB
comments (?)
stdin
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suresh
stdout
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570158749
18  354177701   �   18
20  130954261      20
17  312376972   �   17
4  572039877   �   4
18  354177701   �   18
7  127640768   �   7
https://ideone.com/hD2MwV
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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