auto merge of #10555 : TeXitoi/rust/pidigits-resurected, r=alexcrichton
Changes: * default value when no args * license * removed libc printing * use extra::bigint instead of handmade gmp binding The drawback is that it's 2 order of magnitude slower, the good news is that there is a good bench for extra::bigint.
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// xfail-test
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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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extern mod extra;
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use std::cast::transmute;
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use std::from_str::FromStr;
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use std::libc::{STDOUT_FILENO, c_char, c_int, c_uint, c_void, fdopen, fputc};
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use std::libc::{fputs};
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use std::ptr::null;
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struct mpz_t {
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_mp_alloc: c_int,
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_mp_size: c_int,
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_mp_limb_t: *c_void,
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}
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impl mpz_t {
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fn new() -> mpz_t {
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mpz_t {
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_mp_alloc: 0,
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_mp_size: 0,
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_mp_limb_t: null(),
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}
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}
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}
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#[link_args="-lgmp"]
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extern {
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#[link_name="__gmpz_add"]
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fn mpz_add(x: *mpz_t, y: *mpz_t, z: *mpz_t);
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#[link_name="__gmpz_cmp"]
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fn mpz_cmp(x: *mpz_t, y: *mpz_t) -> c_int;
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#[link_name="__gmpz_fdiv_qr"]
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fn mpz_fdiv_qr(a: *mpz_t, b: *mpz_t, c: *mpz_t, d: *mpz_t);
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#[link_name="__gmpz_get_ui"]
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fn mpz_get_ui(x: *mpz_t) -> c_uint;
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#[link_name="__gmpz_init"]
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fn mpz_init(x: *mpz_t);
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#[link_name="__gmpz_init_set_ui"]
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fn mpz_init_set_ui(x: *mpz_t, y: c_uint);
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#[link_name="__gmpz_mul_2exp"]
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fn mpz_mul_2exp(x: *mpz_t, y: *mpz_t, z: c_uint);
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#[link_name="__gmpz_mul_ui"]
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fn mpz_mul_ui(x: *mpz_t, y: *mpz_t, z: c_uint);
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#[link_name="__gmpz_submul_ui"]
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fn mpz_submul_ui(x: *mpz_t, y: *mpz_t, z: c_uint);
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}
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use std::num::One;
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use std::num::Zero;
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use std::num::FromPrimitive;
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use extra::bigint::BigInt;
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struct Context {
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numer: mpz_t,
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accum: mpz_t,
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denom: mpz_t,
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tmp1: mpz_t,
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tmp2: mpz_t,
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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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unsafe {
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let mut result = Context {
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numer: mpz_t::new(),
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accum: mpz_t::new(),
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denom: mpz_t::new(),
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tmp1: mpz_t::new(),
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tmp2: mpz_t::new(),
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};
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mpz_init(&result.tmp1);
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mpz_init(&result.tmp2);
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mpz_init_set_ui(&result.numer, 1);
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mpz_init_set_ui(&result.accum, 0);
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mpz_init_set_ui(&result.denom, 1);
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result
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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 extract_digit(&mut self) -> i32 {
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unsafe {
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if mpz_cmp(&self.numer, &self.accum) > 0 {
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return -1;
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}
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// Compute (numer * 3 + accum) / denom
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mpz_mul_2exp(&self.tmp1, &self.numer, 1);
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mpz_add(&self.tmp1, &self.tmp1, &self.numer);
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mpz_add(&self.tmp1, &self.tmp1, &self.accum);
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mpz_fdiv_qr(&self.tmp1, &self.tmp2, &self.tmp1, &self.denom);
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// Now, if (numer * 4 + accum) % denom...
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mpz_add(&self.tmp2, &self.tmp2, &self.numer);
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// ... is normalized, then the two divisions have the same result.
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if mpz_cmp(&self.tmp2, &self.denom) >= 0 {
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return -1;
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}
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mpz_get_ui(&self.tmp1) as i32
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}
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fn from_int(i: int) -> BigInt {
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FromPrimitive::from_int(i).unwrap()
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}
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fn next_term(&mut self, k: u32) {
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unsafe {
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let y2 = k*2 + 1;
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mpz_mul_2exp(&self.tmp1, &self.numer, 1);
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mpz_add(&self.accum, &self.accum, &self.tmp1);
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mpz_mul_ui(&self.accum, &self.accum, y2);
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mpz_mul_ui(&self.numer, &self.numer, k);
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mpz_mul_ui(&self.denom, &self.denom, y2);
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}
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fn extract_digit(&self) -> int {
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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_int(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_int().unwrap()
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}
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fn eliminate_digit(&mut self, d: u32) {
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unsafe {
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mpz_submul_ui(&self.accum, &self.denom, d);
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mpz_mul_ui(&self.accum, &self.accum, 10);
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mpz_mul_ui(&self.numer, &self.numer, 10);
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}
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fn next_term(&mut self, k: int) {
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let y2 = Context::from_int(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_int(k);
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self.denom = self.denom * y2;
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}
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fn eliminate_digit(&mut self, d: int) {
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let d = Context::from_int(d);
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let ten = Context::from_int(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: u32) {
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unsafe {
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let mode = "w";
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let stdout = fdopen(STDOUT_FILENO as c_int, transmute(&mode[0]));
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fn pidigits(n: int) {
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let mut k = 0;
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let mut context = Context::new();
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let mut d: i32;
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let mut i: u32 = 0, k: u32 = 0, m: u32;
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let mut context = Context::new();
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for i in range(1, n + 1) {
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let mut d;
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loop {
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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 {
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break;
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}
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}
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fputc((d as c_int) + ('0' as c_int), stdout);
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i += 1;
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m = i % 10;
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if m == 0 {
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let res = fmt!("\t:%d\n", i as int);
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fputs(transmute(&res[0]), stdout);
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}
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if i >= n {
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break;
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}
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context.eliminate_digit(d as u32);
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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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if m != 0 {
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m = 10 - m;
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while m != 0 {
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m -= 1;
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fputc(' ' as c_int, stdout);
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}
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let res = fmt!("\t:%d\n", i as int);
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fputs(transmute(&res[0]), stdout);
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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 range(m, 10) {print(" ");}
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print!("\t:{}\n", n);
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}
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}
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fn main() {
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let n: u32 = FromStr::from_str(os::args()[1]).get();
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let args = std::os::args();
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let n = if args.len() < 2 {
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512
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} else {
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FromStr::from_str(args[1]).unwrap()
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};
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pidigits(n);
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}
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