Interval screening method, interval screening

Interval screening method, interval screening

2016.1.26

 

The subject idea is consistent with the previous two screening methods, but the data range in general questions is relatively large (a <B <= 10 ^ 12 ), but there is also a condition that is conducive to us (B-a <= 10 ^ 6)

It is very simple. According to our well-known theory, the minimum prime factor of the sum of values within B is not greater than √ B, so we can sieve out [1, √ B] use the prime numbers to sieve out the sum of [a, B.

 

Typical Example: Number of prime numbers in a range