solution 5
parent
c1dfb112db
commit
727c36e795
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@ -0,0 +1,8 @@
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pub fn gcd(mut a: u64, mut b: u64) -> u64 {
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while b != 0 {
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let t = a;
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a = b;
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b = t % b;
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}
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a
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}
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@ -1,6 +1,8 @@
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pub mod prime;
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pub mod math;
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pub mod problem_001;
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pub mod problem_002;
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pub mod problem_003;
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pub mod problem_004;
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pub mod problem_005;
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@ -14,7 +14,8 @@ fn subfactors(mut n: u64, p: u64) -> (u64, Vec<u64>) {
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(n, subfactors)
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}
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pub fn trial_factorization(mut n: u64) -> Vec<u64> {
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pub fn trial_factorization(n: u64) -> Vec<u64> {
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let mut n = n;
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let mut factors = Vec::new();
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let (num, division_by_two) = subfactors(n, 2);
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@ -42,6 +43,24 @@ pub fn trial_factorization(mut n: u64) -> Vec<u64> {
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factors
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}
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fn root(n: u64, f: u64) -> u64 {
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let mut n = n;
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let mut result = 0;
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while n % f == 0 {
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result += 1;
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n /= f;
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}
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result
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}
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pub fn prime_factorization(n: u64) -> Vec<(u64, u64)> {
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let factors = trial_factorization(n);
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let exponents = factors.iter().map( |&f| root(n, f) );
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factors.iter().zip(exponents).map( |(&i, j)| (i, j) ).collect()
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}
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#[cfg(test)]
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mod tests {
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use euler::prime::trial_factorization;
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@ -0,0 +1,21 @@
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use euler::math;
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fn smallest_divisible_by_all_up_to(n: u64) -> u64 {
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(2..n).fold(1, |acc, i| {
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acc * i / math::gcd(i, acc)
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})
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}
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pub fn solution() -> u64 {
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smallest_divisible_by_all_up_to(20)
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}
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#[cfg(test)]
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mod tests {
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use euler::problem_005::solution;
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#[test]
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fn problem_005() {
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assert_eq!(solution(), 232_792_560);
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}
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}
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