62 lines
1.3 KiB
Rust
62 lines
1.3 KiB
Rust
/*
|
|
Copyright © 2017 Jörg Sommer <joerg@alea.gnuu.de>
|
|
|
|
License: MIT https://opensource.org/licenses/MIT
|
|
*/
|
|
|
|
//////
|
|
//
|
|
// Solution of Euler 87 https://projecteuler.net/problem=87
|
|
//
|
|
fn gen_prime_numbers(limit: u32) -> Vec<u32> {
|
|
let mut ret = vec![2, 3];
|
|
|
|
let mut num = *ret.last().unwrap();
|
|
'num: while num + 2 <= limit {
|
|
num += 2;
|
|
for i in 3..((num as f32).sqrt() as u32 + 1) {
|
|
if num % i == 0 {
|
|
continue 'num;
|
|
}
|
|
}
|
|
ret.push(num);
|
|
}
|
|
|
|
ret
|
|
}
|
|
|
|
fn main() {
|
|
const LIMIT: u32 = 50_000_000;
|
|
|
|
// println!("pn {:?}", gen_prime_numbers(500));
|
|
let pn = gen_prime_numbers((LIMIT as f32).sqrt() as u32);
|
|
|
|
println!("There are {} numbers below sqrt(50.000.000)", pn.len());
|
|
|
|
let mut nums = Vec::new();
|
|
|
|
for pn2 in pn.iter() {
|
|
let pow2 = pn2.pow(2);
|
|
|
|
for pn3 in pn.iter() {
|
|
let sum = pow2 + pn3.pow(3);
|
|
if sum >= LIMIT {
|
|
break;
|
|
}
|
|
|
|
for pn4 in pn.iter() {
|
|
let sum2 = sum + pn4.pow(4);
|
|
if sum2 >= LIMIT {
|
|
break;
|
|
}
|
|
|
|
nums.push(sum2);
|
|
}
|
|
}
|
|
}
|
|
|
|
nums.sort();
|
|
nums.dedup();
|
|
|
|
println!("Answer {}", nums.len());
|
|
}
|