142 lines
4.1 KiB
Rust
142 lines
4.1 KiB
Rust
use std::collections::{HashMap, HashSet};
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use utils::{
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fraction::Fraction,
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number::{Number, Sign},
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};
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fn main() {
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println!("Start");
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let mut longest = (0, 0);
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for denominator in 2..1000 {
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let f = Fraction::new(1.into(), denominator.into()).unwrap();
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if let Some(rep) = get_recurring(&f) {
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if longest.1 < rep.digits.len() {
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longest = (denominator, rep.digits.len());
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}
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}
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}
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println!("longest {}", longest.0);
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}
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pub fn get_recurring(fraction: &Fraction) -> Option<Number> {
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let mut div_memory = HashMap::new();
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let mut rem_memory = HashSet::new();
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rem_memory.insert(1.into());
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let mut div_with = fraction.numerator.clone();
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let mut rational = Vec::new();
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if div_with < fraction.denominator {
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div_with = div_with * 10;
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}
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loop {
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while div_with < fraction.denominator {
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rational.push(0);
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div_memory
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.entry(0)
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.and_modify(|value| *value += 1)
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.or_insert(1);
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div_with = div_with * 10;
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rem_memory.insert(div_with.clone());
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}
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let (div, rem) =
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Number::div_with_rem(div_with.clone(), fraction.denominator.clone()).unwrap();
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if rem == 0.into() {
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return None;
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}
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let next_digit = div.digits[0];
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if div_memory.contains_key(&next_digit) && rem_memory.contains(&rem) && next_digit != 0 {
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let mut digits = vec![];
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if div_memory.values().min() != div_memory.values().max() {
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rational.push(div.digits[0]);
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digits = rational;
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let (l, r) = digits.split_at(digits.len() / 2);
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if l == r {
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digits = l.to_vec();
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}
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} else {
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let idx = rational
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.iter()
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.position(|digit| digit == &div.digits[0])
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.unwrap();
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if idx == rational.len() - 1 {
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digits.push(div.digits[0]);
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} else {
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for digit in &rational[idx..] {
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if digits.contains(digit) {
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break;
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}
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digits.push(*digit);
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}
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}
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}
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return Some(Number {
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digits,
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sign: Sign::Positif,
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});
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}
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div_memory
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.entry(next_digit)
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.and_modify(|count| *count += 1)
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.or_insert(1);
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rem_memory.insert(rem.clone());
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rational.push(div.digits[0]);
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div_with = rem * 10;
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}
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}
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#[cfg(test)]
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mod test {
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use utils::{fraction::Fraction, number::Number};
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use crate::get_recurring;
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#[test]
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fn test_1_div_2() {
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let f = Fraction::new(1.into(), 2.into()).unwrap();
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let rep = get_recurring(&f);
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assert_eq!(rep, None);
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}
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#[test]
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fn test_1_div_6() {
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let f = Fraction::new(1.into(), 6.into()).unwrap();
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let rep = get_recurring(&f);
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assert_eq!(rep, Some(Number::from("6")));
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}
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#[test]
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fn test_1_div_7() {
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let f = Fraction::new(1.into(), 7.into()).unwrap();
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let rep = get_recurring(&f);
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assert_eq!(rep, Some(Number::from("142857")));
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}
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#[test]
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fn test_1_div_11() {
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let f = Fraction::new(1.into(), 11.into()).unwrap();
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let rep = get_recurring(&f);
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assert_eq!(rep, Some(Number::from("09")));
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}
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#[test]
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fn test_1_div_12() {
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let f = Fraction::new(1.into(), 12.into()).unwrap();
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let rep = get_recurring(&f);
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assert_eq!(rep, Some(Number::from("3")));
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}
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#[test]
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fn test_1_div_14() {
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let f = Fraction::new(1.into(), 14.into()).unwrap();
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let rep = get_recurring(&f);
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assert_eq!(rep, Some(Number::from("714285")));
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}
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#[test]
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fn test_1_div_101() {
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let f = Fraction::new(1.into(), 101.into()).unwrap();
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let rep = get_recurring(&f);
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assert_eq!(rep, Some(Number::from("0099")));
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}
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}
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