Coin de Gamma
11 months ago
1 changed files with 105 additions and 0 deletions
@ -0,0 +1,105 @@
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fn cancel(n: u32, k: u8) -> u32 { |
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let mut res = 0u32; |
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let mut ds = Vec::new(); |
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let mut nn = n; |
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while nn > 0 { |
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let dd = nn % 10; |
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if dd != k as u32 { |
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ds.push(nn % 10); |
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} |
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nn /= 10; |
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} |
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for x in ds.iter().rev() { |
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res *= 10; |
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res += x; |
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} |
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return res; |
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} |
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fn gcd(mut a: u32, mut b: u32) -> u32 { |
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while b != 0 { |
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let remainder = a % b; |
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a = b; |
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b = remainder; |
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} |
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a |
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} |
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struct Fr { |
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n: u32, |
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d: u32 |
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} |
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impl Fr { |
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fn from(n: u32, d: u32) -> Fr { |
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return Fr { n: n, d: d }; |
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} |
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fn simple(&self) -> Fr { |
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let g = gcd(self.n, self.d); |
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let n = self.n / g; |
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let d = self.d / g; |
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return Fr { n: n, d: d }; |
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} |
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fn print(&self) { |
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println!("{}/{}", self.n, self.d); |
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} |
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fn eq(&self, other: &Fr) -> bool { |
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let a = self.simple(); |
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let b = other.simple(); |
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return a.n == b.n && a.d == b.d; |
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} |
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fn ds(&self) -> Vec<u8> { |
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let mut res = Vec::new(); |
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let mut n = self.n; |
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let mut d = self.d; |
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while n > 0 { |
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res.push((n % 10) as u8); |
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n /= 10; |
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} |
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while d > 0 { |
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res.push((d % 10) as u8); |
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d /= 10; |
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} |
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return res; |
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} |
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fn cancel(&self, k: u8) -> Fr { |
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let n = cancel(self.n, k); |
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let d = cancel(self.d, k); |
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return Fr{ n: n, d: d }; |
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} |
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fn can_cancel(&self, k: u8) -> bool { |
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return cancel(self.n, k) != 0 && cancel(self.d, k) != 0; |
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} |
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fn test(&self) -> bool { |
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let ds = self.ds(); |
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for k in ds { |
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if !self.can_cancel(k) { continue; } |
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let cn = self.cancel(k); |
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if self.eq(&cn) { |
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return true; |
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} |
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} |
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return false; |
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} |
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} |
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fn main() { |
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let mut res_n = 1; |
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let mut res_d = 1; |
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for n in 10..99 { |
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for d in n+1..99 { |
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//println!("{}/{}", n, d);
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if n % 10 == 0 && d % 10 == 0 { continue; } |
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let f = Fr::from(n, d); |
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if f.test() { |
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f.print(); |
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res_n *= n; |
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res_d *= d; |
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} |
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} |
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} |
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let res_fr = Fr::from(res_n, res_d).simple(); |
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println!("{}", res_fr.d); |
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} |
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