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use crate::natural::InnerNatural::{Large, Small};
use crate::natural::Natural;
use crate::platform::Limb;
use malachite_base::num::logic::traits::CountOnes;
// Interpreting a slice of `Limb`s, as the limbs (in ascending order) of a `Natural`, counts the
// number of ones in the binary expansion of the `Natural`.
//
// # Worst-case complexity
// $T(n) = O(n)$
//
// $M(n) = O(1)$
//
// where $T$ is time, $M$ is additional memory, and $n$ is `xs.len()`.
pub_crate_test! {limbs_count_ones(xs: &[Limb]) -> u64 {
xs.iter().map(|&x| CountOnes::count_ones(x)).sum()
}}
impl CountOnes for &Natural {
/// Counts the number of ones in the binary expansion of a [`Natural`].
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `self.significant_bits()`.
///
/// # Examples
/// ```
/// extern crate malachite_base;
///
/// use malachite_base::num::arithmetic::traits::Pow;
/// use malachite_base::num::basic::traits::Zero;
/// use malachite_base::num::logic::traits::CountOnes;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Natural::ZERO.count_ones(), 0);
/// // 105 = 1101001b
/// assert_eq!(Natural::from(105u32).count_ones(), 4);
/// // 10^12 = 1110100011010100101001010001000000000000b
/// assert_eq!(Natural::from(10u32).pow(12).count_ones(), 13);
/// ```
fn count_ones(self) -> u64 {
match *self {
Natural(Small(small)) => CountOnes::count_ones(small),
Natural(Large(ref limbs)) => limbs_count_ones(limbs),
}
}
}