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