Hello everyone,
I encountered this problem from a company's job seeking website. I am a newbit to PHP field, but I would really like to learn this language since it is so popular in the web application development field. Could you kindly to help me get started? Thanks a lot.
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Prime Bits
First, consider a function P(x) where:
P(x) returns:
true if the number of 1 bits set in the
binary representation of x is prime,
false otherwise.
For example, P(239) returns true, while P(51) returns false.
Next, consider the following function prime_bits:
uint64_t prime_bits(uint64_t a, uint64_t b);
A call to prime_bits(a, b) returns the number of values between a and b inclusive for which P(x) is true. For example, prime_bits(4, 10) returns 5. Your job is to implement the prime_bits function.
Your implementation should be efficient, and it should be wrapped up nicely such that one can specify a and b on the commandline when running your program. You may expect the range of a and b to be limited to non-negative 64-bit integers, though it would certainly be uncouth for your algorithm to break down for larger values.
