// Copyright © 2024 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See .
use malachite_base::num::arithmetic::traits::BinomialCoefficient;
use malachite_base::num::basic::signeds::PrimitiveSigned;
use malachite_base::num::basic::unsigneds::PrimitiveUnsigned;
use malachite_base::test_util::generators::{
signed_gen, signed_gen_var_2, signed_pair_gen_var_11, signed_pair_gen_var_12, unsigned_gen,
unsigned_gen_var_1, unsigned_pair_gen_var_28, unsigned_pair_gen_var_44,
};
use std::panic::catch_unwind;
#[test]
fn test_binomial_coefficient() {
fn test_u(n: T, k: T, out: T) {
assert_eq!(T::binomial_coefficient(n, k), out);
}
test_u::(0, 0, 1);
test_u::(1, 0, 1);
test_u::(1, 1, 1);
test_u::(2, 0, 1);
test_u::(2, 1, 2);
test_u::(2, 2, 1);
test_u::(3, 0, 1);
test_u::(3, 1, 3);
test_u::(3, 2, 3);
test_u::(3, 3, 1);
test_u::(4, 0, 1);
test_u::(4, 1, 4);
test_u::(4, 2, 6);
test_u::(4, 3, 4);
test_u::(4, 4, 1);
test_u::(1, 2, 0);
test_u::(10, 5, 252);
test_u::(100, 50, 100891344545564193334812497256);
fn test_i(n: T, k: T, out: T) {
assert_eq!(T::binomial_coefficient(n, k), out);
}
test_i::(0, 0, 1);
test_i::(1, 0, 1);
test_i::(1, 1, 1);
test_i::(2, 0, 1);
test_i::(2, 1, 2);
test_i::(2, 2, 1);
test_i::(3, 0, 1);
test_i::(3, 1, 3);
test_i::(3, 2, 3);
test_i::(3, 3, 1);
test_i::(4, 0, 1);
test_i::(4, 1, 4);
test_i::(4, 2, 6);
test_i::(4, 3, 4);
test_i::(4, 4, 1);
test_i::(1, 2, 0);
test_i::(10, 5, 252);
test_i::(100, 50, 100891344545564193334812497256);
test_i::(-1, 0, 1);
test_i::(-1, 1, -1);
test_i::(-2, 0, 1);
test_i::(-2, 1, -2);
test_i::(-2, 2, 3);
test_i::(-3, 0, 1);
test_i::(-3, 1, -3);
test_i::(-3, 2, 6);
test_i::(-3, 3, -10);
test_i::(-1, 2, 1);
test_i::(-10, 5, -2002);
test_i::(-80, 50, 1828256793482238093393785743858493760);
test_i::(-128, 1, -128);
test_i::(-2, 127, -128);
}
#[test]
pub fn binomial_coefficient_fail() {
assert_panic!(u8::binomial_coefficient(11, 5));
assert_panic!(u128::binomial_coefficient(1000000, 1000));
assert_panic!(i8::binomial_coefficient(11, 5));
assert_panic!(i128::binomial_coefficient(1000000, 1000));
assert_panic!(i8::binomial_coefficient(1, -1));
}
#[test]
fn test_checked_binomial_coefficient() {
fn test_u(n: T, k: T, out: Option) {
assert_eq!(T::checked_binomial_coefficient(n, k), out);
}
test_u::(0, 0, Some(1));
test_u::(1, 0, Some(1));
test_u::(1, 1, Some(1));
test_u::(2, 0, Some(1));
test_u::(2, 1, Some(2));
test_u::(2, 2, Some(1));
test_u::(3, 0, Some(1));
test_u::(3, 1, Some(3));
test_u::(3, 2, Some(3));
test_u::(3, 3, Some(1));
test_u::(4, 0, Some(1));
test_u::(4, 1, Some(4));
test_u::(4, 2, Some(6));
test_u::(4, 3, Some(4));
test_u::(4, 4, Some(1));
test_u::(1, 2, Some(0));
test_u::(10, 5, Some(252));
test_u::(100, 50, Some(100891344545564193334812497256));
test_u::(11, 5, None);
test_u::(1000000, 1000, None);
fn test_i(n: T, k: T, out: Option) {
assert_eq!(T::checked_binomial_coefficient(n, k), out);
}
test_i::(0, 0, Some(1));
test_i::(1, 0, Some(1));
test_i::(1, 1, Some(1));
test_i::(2, 0, Some(1));
test_i::(2, 1, Some(2));
test_i::(2, 2, Some(1));
test_i::(3, 0, Some(1));
test_i::(3, 1, Some(3));
test_i::(3, 2, Some(3));
test_i::(3, 3, Some(1));
test_i::(4, 0, Some(1));
test_i::(4, 1, Some(4));
test_i::(4, 2, Some(6));
test_i::(4, 3, Some(4));
test_i::(4, 4, Some(1));
test_i::(1, 2, Some(0));
test_i::(10, 5, Some(252));
test_i::(100, 50, Some(100891344545564193334812497256));
test_i::(-1, 0, Some(1));
test_i::(-1, 1, Some(-1));
test_i::(-2, 0, Some(1));
test_i::(-2, 1, Some(-2));
test_i::(-2, 2, Some(3));
test_i::(-3, 0, Some(1));
test_i::(-3, 1, Some(-3));
test_i::(-3, 2, Some(6));
test_i::(-3, 3, Some(-10));
test_i::(-1, 2, Some(1));
test_i::(-10, 5, Some(-2002));
test_i::(-80, 50, Some(1828256793482238093393785743858493760));
test_i::(-128, 1, Some(-128));
test_i::(-2, 127, Some(-128));
test_i::(11, 5, None);
test_i::(1000000, 1000, None);
test_i::(1, -1, None);
}
fn binomial_coefficient_helper_unsigned() {
unsigned_pair_gen_var_44::().test_properties(|(n, k)| {
let b = T::binomial_coefficient(n, k);
assert_eq!(b == T::ZERO, n < k);
if n >= k {
assert_eq!(T::binomial_coefficient(n, n - k), b);
}
if n != T::ZERO && k != T::ZERO {
let c = T::binomial_coefficient(n - T::ONE, k - T::ONE);
assert_eq!(T::binomial_coefficient(n - T::ONE, k) + c, b);
let gcd = n.gcd(k);
assert_eq!(c / (k / gcd) * (n / gcd), b);
}
});
unsigned_gen::().test_properties(|n| {
assert_eq!(T::binomial_coefficient(n, T::ZERO), T::ONE);
assert_eq!(T::binomial_coefficient(n, T::ONE), n);
});
unsigned_gen_var_1::().test_properties(|n| {
assert_eq!(T::binomial_coefficient(n, n), T::ONE);
assert_eq!(T::binomial_coefficient(n, n - T::ONE), n);
assert_eq!(T::binomial_coefficient(T::ZERO, n), T::ZERO);
});
}
fn binomial_coefficient_helper_signed() {
signed_pair_gen_var_12::().test_properties(|(n, k)| {
let b = T::binomial_coefficient(n, k);
assert_eq!(b == T::ZERO, n >= T::ZERO && n < k);
if n >= k {
assert_eq!(T::binomial_coefficient(n, n - k), b);
}
if n != T::MIN && k != T::ZERO {
if let Some(c) = T::checked_binomial_coefficient(n - T::ONE, k) {
assert_eq!(c + T::binomial_coefficient(n - T::ONE, k - T::ONE), b);
}
}
if n != T::MIN {
if let Some(s) = (n - T::ONE).checked_add(k) {
if let Some(mut b_alt) = T::checked_binomial_coefficient(s, k) {
if k.odd() {
b_alt.neg_assign();
}
assert_eq!(T::binomial_coefficient(-n, k), b_alt);
}
}
}
});
signed_gen::().test_properties(|n| {
assert_eq!(T::binomial_coefficient(n, T::ONE), n);
assert_eq!(T::binomial_coefficient(n, T::ZERO), T::ONE);
});
signed_gen_var_2::().test_properties(|n| {
assert_eq!(T::binomial_coefficient(n, n), T::ONE);
if n != T::ZERO {
assert_eq!(T::binomial_coefficient(n, n - T::ONE), n);
assert_eq!(T::binomial_coefficient(T::ZERO, n), T::ZERO);
}
});
}
#[test]
fn binomial_coefficient_properties() {
apply_fn_to_unsigneds!(binomial_coefficient_helper_unsigned);
apply_fn_to_signeds!(binomial_coefficient_helper_signed);
}
fn checked_binomial_coefficient_helper_unsigned() {
unsigned_pair_gen_var_28::().test_properties(|(n, k)| {
if let Some(b) = T::checked_binomial_coefficient(n, k) {
assert_eq!(T::binomial_coefficient(n, k), b);
}
});
}
fn checked_binomial_coefficient_helper_signed() {
signed_pair_gen_var_11::().test_properties(|(n, k)| {
if let Some(b) = T::checked_binomial_coefficient(n, k) {
assert_eq!(T::binomial_coefficient(n, k), b);
}
});
}
#[test]
fn checked_binomial_coefficient_properties() {
apply_fn_to_unsigneds!(checked_binomial_coefficient_helper_unsigned);
apply_fn_to_signeds!(checked_binomial_coefficient_helper_signed);
}