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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define int long long int
  4.  
  5. const int MAXN = 1e6;
  6. vector<int> spf(MAXN + 1, 0);
  7.  
  8. void computeSpf(){
  9.     for (int i = 2; i <= MAXN; i++){
  10.     	spf[i] = i;
  11.     }
  12.  
  13.     // starting the sieve process
  14.  
  15.     for (int i = 2; i * i <= MAXN; i++){
  16.     	if(spf[i] == i){
  17.     		for (int j = i*i; j <= MAXN; j += i){
  18.     			if(spf[j] == j){
  19.     				spf[j] = i;
  20.     			}
  21.     		}
  22.     	}
  23.     }
  24.  
  25. }
  26.  
  27.  
  28. signed main() {
  29.     ios_base::sync_with_stdio(0);
  30.     cin.tie(0); cout.tie(0);
  31.  
  32.     // int t; cin >> t;
  33.     // while (t--) {
  34.     //     solve();
  35.     // }
  36.     computeSpf();
  37.     vector<int> input = {2, 14, 11, 36, 49, 7, 21, 44, 69, 501, 67, 1000};
  38.  
  39.     for (int i : input){
  40.     	cout << "The smallest prime Factor of " << i << " is: " << spf[i] << endl;
  41.     }
  42.     return 0;
  43. }
Success #stdin #stdout 0.02s 10860KB
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stdin
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Standard input is empty
stdout
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The smallest prime Factor of 2 is: 2
The smallest prime Factor of 14 is: 2
The smallest prime Factor of 11 is: 11
The smallest prime Factor of 36 is: 2
The smallest prime Factor of 49 is: 7
The smallest prime Factor of 7 is: 7
The smallest prime Factor of 21 is: 3
The smallest prime Factor of 44 is: 2
The smallest prime Factor of 69 is: 3
The smallest prime Factor of 501 is: 3
The smallest prime Factor of 67 is: 67
The smallest prime Factor of 1000 is: 2
https://ideone.com/Q2DQod
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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