P210: Calculate Euler's totient function phi(m) (2) 「重复」

See problem 2.09 for the definition of Euler's totient function. If the list of the prime factors of a number m is known in the form of problem 2.03 then the function phi(m) can be efficiently calculated as follows: Let [[p1,m1],[p2,m2],[p3,m3],...] be the list of prime factors (and their multiplicities) of a given number m. Then phi(m) can be calculated with the following formula:

phi(m) = (p1 - 1) p1**(m1 - 1) (p2 - 1) p2**(m2 - 1) (p3 - 1) p3**(m3 - 1) ...

Note that a**b stands for the b'th power of a.See problem 2.09 for the definition of Euler's totient function. If the list of the prime factors of a number m is known in the form of problem 2.03 then the function phi(m) can be efficiently calculated as follows: Let [[p1,m1],[p2,m2],[p3,m3],...] be the list of prime factors (and their multiplicities) of a given number m. Then phi(m) can be calculated with the following formula:

在P209已经使用了这个方法～～