140 lines
3.9 KiB
Rust
140 lines
3.9 KiB
Rust
// The Computer Language Benchmarks Game
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// http://benchmarksgame.alioth.debian.org/
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//
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// contributed by the Rust Project Developers
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// Copyright (c) 2013-2014 The Rust Project Developers
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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//
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// - Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//
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// - Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in
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// the documentation and/or other materials provided with the
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// distribution.
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//
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// - Neither the name of "The Computer Language Benchmarks Game" nor
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// the name of "The Computer Language Shootout Benchmarks" nor the
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// names of its contributors may be used to endorse or promote
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// products derived from this software without specific prior
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// written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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// OF THE POSSIBILITY OF SUCH DAMAGE.
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#![feature(core)]
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#![feature(test)]
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extern crate num;
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extern crate test;
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use std::str::FromStr;
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use std::num::{FromPrimitive, ToPrimitive};
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use test::Bencher;
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use num::{BigInt, Integer, One, Zero};
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struct Context {
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numer: BigInt,
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accum: BigInt,
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denom: BigInt,
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}
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impl Context {
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fn new() -> Context {
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Context {
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numer: One::one(),
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accum: Zero::zero(),
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denom: One::one(),
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}
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}
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fn from_i32(i: i32) -> BigInt {
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FromPrimitive::from_i32(i).unwrap()
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}
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fn extract_digit(&self) -> i32 {
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if self.numer > self.accum {return -1;}
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let (q, r) =
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(&self.numer * Context::from_i32(3) + &self.accum)
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.div_rem(&self.denom);
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if r + &self.numer >= self.denom {return -1;}
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q.to_i32().unwrap()
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}
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fn next_term(&mut self, k: i32) {
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let y2 = Context::from_i32(k * 2 + 1);
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self.accum = (&self.accum + (&self.numer << 1)) * &y2;
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self.numer = &self.numer * Context::from_i32(k);
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self.denom = &self.denom * y2;
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}
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fn eliminate_digit(&mut self, d: i32) {
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let d = Context::from_i32(d);
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let ten = Context::from_i32(10);
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self.accum = (&self.accum - &self.denom * d) * &ten;
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self.numer = &self.numer * ten;
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}
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}
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fn pidigits(n: isize) {
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let mut k = 0;
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let mut context = Context::new();
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for i in (1..(n+1)) {
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let mut d;
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loop {
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k += 1;
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context.next_term(k);
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d = context.extract_digit();
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if d != -1 {break;}
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}
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print!("{}", d);
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if i % 10 == 0 {print!("\t:{}\n", i);}
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context.eliminate_digit(d);
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}
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let m = n % 10;
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if m != 0 {
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for _ in (m..10) { print!(" "); }
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print!("\t:{}\n", n);
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}
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}
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static DEFAULT_DIGITS: isize = 512;
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#[bench]
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fn use_bencher(b: &mut Bencher) {
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b.iter(|| pidigits(DEFAULT_DIGITS))
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}
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#[allow(dead_code)]
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fn main() {
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let args = std::env::args().collect::<Vec<_>>();
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let n = if args.len() < 2 {
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DEFAULT_DIGITS
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} else {
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FromStr::from_str(args[1].as_slice()).unwrap()
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};
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pidigits(n);
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}
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