ZOJ 4846 GCD Reduce (mathematical analysis)

ZOJ 4846 GCD Reduce (mathematical analysis)

 

Question:

Given a series with n length, you can select a Binary Group (a [I], a [j]) to replace them with their maximum common approx.

Then I asked if I could change all of them to 1 in 5 * n operations,

 

Analysis:

Because each operation is changed to GCD, the number of n GCD must be 1. If it is not 1, it cannot be changed to 1.

Then you just need to construct a method. The number from 1 to n can be changed to 1;

 

The Code is as follows:

 

# Include

 
  
# Include

  
   
# Include

   
    
Using namespace std; const int maxn = 1e5 + 10; int a [maxn]; int gcd (int a, int B) {if (B) return gcd (B, a % B); return a;} int main () {int cas = 1, n; while (~ Scanf (% d, & n) {int mmin = 1999999999, num = 0; for (int I = 0; I