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|
use std::cmp::max;
use std::fmt;
use std::ops::{Add, Mul, Sub};
pub struct Number {
radix: usize,
digits: Vec<u8>,
}
impl Number {
pub fn parse(snum: &str, radix: usize) -> Result<Number, &str> {
let snum = snum.as_bytes();
let mut digits = Vec::new();
for i in (0..snum.len()).rev() {
match Number::parse_digit(snum[i]) {
Some(digit) => {
if digit as usize >= radix {
return Err("Аргумент не является числом");
} else {
digits.push(digit);
}
}
None => {
return Err("Аргумент не является числом");
}
}
}
return Ok(Number { radix, digits });
}
pub fn len(&self) -> usize {
self.digits.len()
}
fn parse_digit(c: u8) -> Option<u8> {
if c >= 'a' as u8 {
Some(c - 'a' as u8 + 10_u8)
} else if c >= '0' as u8 {
Some(c - '0' as u8)
} else {
None
}
}
fn fix_leading_zeros(mut self) -> Self {
let mut leading = 0;
for i in (1..self.digits.len()).rev() {
if self.digits[i] == 0 {
leading += 1;
} else {
break;
}
}
for _ in 0..leading {
self.digits.pop();
}
return self;
}
}
impl fmt::Display for Number {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
for i in (0..self.digits.len()).rev() {
let digit = if self.digits[i] > 9 {
('a' as u8 - 10 + self.digits[i]) as char
} else {
('0' as u8 + self.digits[i]) as char
};
write!(f, "{}", digit)?;
}
if self.radix != 10 {
write!(f, "_{}", self.radix)?;
}
return Ok(());
}
}
impl Add for Number {
type Output = Self;
fn add(self, other: Self) -> Self::Output {
let mut k = 0;
let len = max(self.len(), other.len());
let mut digits = Vec::new();
for i in 0..len {
let mut digit = 0;
if i < self.len() {
digit += self.digits[i] as usize;
}
if i < other.len() {
digit += other.digits[i] as usize;
}
digit += k;
let (div, rem) = (digit / self.radix, digit % self.radix);
digit = rem;
k = div;
digits.push(digit as u8);
}
if k != 0 {
digits.push(k as u8);
}
return Number {
radix: self.radix,
digits,
};
}
}
impl Sub for Number {
type Output = Self;
fn sub(self, other: Self) -> Self::Output {
let len = max(self.len(), other.len());
let mut digits = Vec::new();
let mut k = 0;
for i in 0..len {
let q1 = if i < self.len() {
self.digits[i] as i64
} else {
0_i64
};
let q2 = if i < other.len() {
other.digits[i] as i64
} else {
0_i64
};
let b = self.radix as i64;
let res = q1 - q2 + k;
let digit = (res + b) % b;
k = if res < 0 { -1 } else { 0 };
digits.push(digit as u8);
}
if k != 0 {
digits.push(k as u8);
}
return Number {
radix: self.radix,
digits,
}
.fix_leading_zeros();
}
}
impl Mul for Number {
type Output = Self;
fn mul(self, other: Self) -> Self::Output {
let n = self.len();
let m = other.len();
let mut digits = vec![0; n + m];
for j in 0..m {
let vj = other.digits[j];
if vj == 0 {
digits[n + j] = 0;
} else {
let mut k = 0;
for i in 0..n {
let ui = self.digits[i];
let t = ui * vj + digits[i + j] + k;
digits[i + j] = t % self.radix as u8;
k = t / self.radix as u8;
}
digits[n + j] = k;
}
}
return Number {
radix: self.radix,
digits,
}
.fix_leading_zeros();
}
}
|
