Pick the best hand(s) from a list of poker hands.
See wikipedia for an overview of poker hands.
Vec<T> where T: Ord
.Ord
types are form a total order: exactly one of a < b
, a == b
, or a > b
must be true."3S 4S 5D 6H JH"
, "3H 4H 5C 6C JD"
.PartialOrd
trait to handle the case of sortable things which do not have a total order. However, it doesn't provide a standard sort
method for Vec<T> where T: PartialOrd
. The standard idiom to sort a vector in this case is your_vec.sort_by(|a, b| a.partial_cmp(b).unwrap_or(Ordering::{Less|Equal|Greater}));
, depending on your needs.PartialOrd
.Refer to the exercism help page for Rust installation and learning resources.
Execute the tests with:
$ cargo test
All but the first test have been ignored. After you get the first test to
pass, open the tests source file which is located in the tests
directory
and remove the #[ignore]
flag from the next test and get the tests to pass
again. Each separate test is a function with #[test]
flag above it.
Continue, until you pass every test.
If you wish to run all ignored tests without editing the tests source file, use:
$ cargo test -- --ignored
To run a specific test, for example some_test
, you can use:
$ cargo test some_test
If the specific test is ignored use:
$ cargo test some_test -- --ignored
To learn more about Rust tests refer to the online test documentation
Make sure to read the Modules chapter if you haven't already, it will help you with organizing your files.
After you have solved the exercise, please consider using the additional utilities, described in the installation guide, to further refine your final solution.
To format your solution, inside the solution directory use
cargo fmt
To see, if your solution contains some common ineffective use cases, inside the solution directory use
cargo clippy --all-targets
Generally you should submit all files in which you implemented your solution (src/lib.rs
in most cases). If you are using any external crates, please consider submitting the Cargo.toml
file. This will make the review process faster and clearer.
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Inspired by the training course from Udacity. https://www.udacity.com/course/viewer#!/c-cs212/
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
use poker::winning_hands;
use std::collections::HashSet;
fn hs_from<'a>(input: &[&'a str]) -> HashSet<&'a str> {
let mut hs = HashSet::new();
for item in input.iter() {
hs.insert(*item);
}
hs
}
/// Test that the expected output is produced from the given input
/// using the `winning_hands` function.
///
/// Note that the output can be in any order. Here, we use a HashSet to
/// abstract away the order of outputs.
fn test<'a, 'b>(input: &[&'a str], expected: &[&'b str]) {
assert_eq!(
hs_from(&winning_hands(input).expect("This test should produce Some value",)),
hs_from(expected)
)
}
#[test]
fn test_single_hand_always_wins() {
test(&["4S 5S 7H 8D JC"], &["4S 5S 7H 8D JC"])
}
#[test]
#[ignore]
fn test_highest_card_of_all_hands_wins() {
test(
&["4D 5S 6S 8D 3C", "2S 4C 7S 9H 10H", "3S 4S 5D 6H JH"],
&["3S 4S 5D 6H JH"],
)
}
#[test]
#[ignore]
fn test_a_tie_has_multiple_winners() {
test(
&[
"4D 5S 6S 8D 3C",
"2S 4C 7S 9H 10H",
"3S 4S 5D 6H JH",
"3H 4H 5C 6C JD",
],
&["3S 4S 5D 6H JH", "3H 4H 5C 6C JD"],
)
}
#[test]
#[ignore]
fn test_high_card_can_be_low_card_in_an_otherwise_tie() {
// multiple hands with the same high cards, tie compares next highest ranked,
// down to last card
test(&["3S 5H 6S 8D 7H", "2S 5D 6D 8C 7S"], &["3S 5H 6S 8D 7H"])
}
#[test]
#[ignore]
fn test_one_pair_beats_high_card() {
test(&["4S 5H 6C 8D KH", "2S 4H 6S 4D JH"], &["2S 4H 6S 4D JH"])
}
#[test]
#[ignore]
fn test_highest_pair_wins() {
test(&["4S 2H 6S 2D JH", "2S 4H 6C 4D JD"], &["2S 4H 6C 4D JD"])
}
#[test]
#[ignore]
fn test_two_pairs_beats_one_pair() {
test(&["2S 8H 6S 8D JH", "4S 5H 4C 8C 5C"], &["4S 5H 4C 8C 5C"])
}
#[test]
#[ignore]
fn test_two_pair_ranks() {
// both hands have two pairs, highest ranked pair wins
test(&["2S 8H 2D 8D 3H", "4S 5H 4C 8S 5D"], &["2S 8H 2D 8D 3H"])
}
#[test]
#[ignore]
fn test_two_pairs_second_pair_cascade() {
// both hands have two pairs, with the same highest ranked pair,
// tie goes to low pair
test(&["2S QS 2C QD JH", "JD QH JS 8D QC"], &["JD QH JS 8D QC"])
}
#[test]
#[ignore]
fn test_two_pairs_last_card_cascade() {
// both hands have two identically ranked pairs,
// tie goes to remaining card (kicker)
test(&["JD QH JS 8D QC", "JS QS JC 2D QD"], &["JD QH JS 8D QC"])
}
#[test]
#[ignore]
fn test_three_of_a_kind_beats_two_pair() {
test(&["2S 8H 2H 8D JH", "4S 5H 4C 8S 4H"], &["4S 5H 4C 8S 4H"])
}
#[test]
#[ignore]
fn test_three_of_a_kind_ranks() {
//both hands have three of a kind, tie goes to highest ranked triplet
test(&["2S 2H 2C 8D JH", "4S AH AS 8C AD"], &["4S AH AS 8C AD"])
}
#[test]
#[ignore]
fn test_three_of_a_kind_cascade_ranks() {
// with multiple decks, two players can have same three of a kind,
// ties go to highest remaining cards
test(&["4S AH AS 7C AD", "4S AH AS 8C AD"], &["4S AH AS 8C AD"])
}
#[test]
#[ignore]
fn test_straight_beats_three_of_a_kind() {
test(&["4S 5H 4C 8D 4H", "3S 4D 2S 6D 5C"], &["3S 4D 2S 6D 5C"])
}
#[test]
#[ignore]
fn test_aces_can_end_a_straight_high() {
// aces can end a straight (10 J Q K A)
test(&["4S 5H 4C 8D 4H", "10D JH QS KD AC"], &["10D JH QS KD AC"])
}
#[test]
#[ignore]
fn test_aces_can_end_a_straight_low() {
// aces can start a straight (A 2 3 4 5)
test(&["4S 5H 4C 8D 4H", "4D AH 3S 2D 5C"], &["4D AH 3S 2D 5C"])
}
#[test]
#[ignore]
fn test_straight_cascade() {
// both hands with a straight, tie goes to highest ranked card
test(&["4S 6C 7S 8D 5H", "5S 7H 8S 9D 6H"], &["5S 7H 8S 9D 6H"])
}
#[test]
#[ignore]
fn test_straight_scoring() {
// even though an ace is usually high, a 5-high straight is the lowest-scoring straight
test(&["2H 3C 4D 5D 6H", "4S AH 3S 2D 5H"], &["2H 3C 4D 5D 6H"])
}
#[test]
#[ignore]
fn test_flush_beats_a_straight() {
test(&["4C 6H 7D 8D 5H", "2S 4S 5S 6S 7S"], &["2S 4S 5S 6S 7S"])
}
#[test]
#[ignore]
fn test_flush_cascade() {
// both hands have a flush, tie goes to high card, down to the last one if necessary
test(&["4H 7H 8H 9H 6H", "2S 4S 5S 6S 7S"], &["4H 7H 8H 9H 6H"])
}
#[test]
#[ignore]
fn test_full_house_beats_a_flush() {
test(&["3H 6H 7H 8H 5H", "4S 5C 4C 5D 4H"], &["4S 5C 4C 5D 4H"])
}
#[test]
#[ignore]
fn test_full_house_ranks() {
// both hands have a full house, tie goes to highest-ranked triplet
test(&["4H 4S 4D 9S 9D", "5H 5S 5D 8S 8D"], &["5H 5S 5D 8S 8D"])
}
#[test]
#[ignore]
fn test_full_house_cascade() {
// with multiple decks, both hands have a full house with the same triplet, tie goes to the pair
test(&["5H 5S 5D 9S 9D", "5H 5S 5D 8S 8D"], &["5H 5S 5D 9S 9D"])
}
#[test]
#[ignore]
fn test_four_of_a_kind_beats_full_house() {
test(&["4S 5H 4D 5D 4H", "3S 3H 2S 3D 3C"], &["3S 3H 2S 3D 3C"])
}
#[test]
#[ignore]
fn test_four_of_a_kind_ranks() {
// both hands have four of a kind, tie goes to high quad
test(&["2S 2H 2C 8D 2D", "4S 5H 5S 5D 5C"], &["4S 5H 5S 5D 5C"])
}
#[test]
#[ignore]
fn test_four_of_a_kind_cascade() {
// with multiple decks, both hands with identical four of a kind, tie determined by kicker
test(&["3S 3H 2S 3D 3C", "3S 3H 4S 3D 3C"], &["3S 3H 4S 3D 3C"])
}
#[test]
#[ignore]
fn test_straight_flush_beats_four_of_a_kind() {
test(&["4S 5H 5S 5D 5C", "7S 8S 9S 6S 10S"], &["7S 8S 9S 6S 10S"])
}
#[test]
#[ignore]
fn test_straight_flush_ranks() {
// both hands have straight flush, tie goes to highest-ranked card
test(&["4H 6H 7H 8H 5H", "5S 7S 8S 9S 6S"], &["5S 7S 8S 9S 6S"])
}
use itertools::Itertools;
pub fn winning_hands<'a>(hands: &[&'a str]) -> Option<Vec<&'a str>> {
let hands = hands
.iter()
.map(|hand| {
let pokerhand = PokerHand::new(
hand.split_whitespace()
.flat_map(|card| Card::new(card))
.collect::<Vec<Card>>()
.as_slice(),
);
(pokerhand, *hand)
})
.sorted_by(|x, y| y.cmp(x))
.collect::<Vec<(PokerHand, &'a str)>>();
if hands.iter().any(|(hand, _)| *hand == PokerHand::Invalid) {
None
} else {
let winner = &hands[0].0;
Some(
hands
.iter()
.take_while(|hand| hand.0 == *winner) // for ties
.map(|h| h.1)
.collect(),
)
}
}
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
enum PokerHand {
Invalid,
HighCard(u8, u8, u8, u8, u8),
OnePair(u8, u8, u8, u8),
TwoPair(u8, u8, u8),
ThreeOfAKind(u8, u8, u8),
Straight(u8),
Flush(u8),
FullHouse(u8, u8),
FourOfAKind(u8, u8),
StraightFlush(u8),
}
impl PokerHand {
fn new(cards: &[Card]) -> Self {
if cards.len() != 5 {
return PokerHand::Invalid;
}
let grouped_cards = cards
.iter()
.sorted_by_key(|c| c.0)
.group_by(|&c| c.0)
.into_iter()
.map(|(_, g)| g.map(|c| c.0).collect())
.sorted_by_key(|v: &Vec<u8>| v.len())
.collect::<Vec<Vec<u8>>>();
let clasi = &grouped_cards
.iter()
.map(|v| v.len())
.collect::<Vec<usize>>();
match &clasi[..] {
[_, 4] => PokerHand::FourOfAKind(grouped_cards[1][0], grouped_cards[0][0]),
[2, 3] => PokerHand::FullHouse(grouped_cards[1][0], grouped_cards[0][0]),
[_, _, 3] => PokerHand::ThreeOfAKind(
grouped_cards[2][0],
grouped_cards[1][0],
grouped_cards[0][0],
),
[_, 2, 2] => PokerHand::TwoPair(
grouped_cards[2][0],
grouped_cards[1][0],
grouped_cards[0][0],
),
[_, _, _, 2] => PokerHand::OnePair(
grouped_cards[3][0],
grouped_cards[0][0],
grouped_cards[0][0],
grouped_cards[0][0],
),
_ => {
// can't find groups, so see if we have straights or flush
let cards: Vec<Card> = cards.iter().sorted_by(|x, y| y.cmp(x)).cloned().collect();
let straight = cards
.windows(2)
.all(|w| w[0].0 == w[1].0 + 1 || w[0].0 == 14 && w[1].0 == 5);
let flush = cards.iter().all(|c| c.1 == cards[0].1);
if !straight && !flush {
PokerHand::HighCard(cards[0].0, cards[1].0, cards[2].0, cards[3].0, cards[4].0)
} else {
// fix situation when we have an ace in cards
let max: u8 = cards
.iter()
.map(|c| if c.0 == 14 { 1 } else { c.0 })
.max()
.unwrap();
if straight && flush {
PokerHand::StraightFlush(max)
} else if straight {
PokerHand::Straight(max)
} else {
PokerHand::Flush(max)
}
}
}
}
}
}
#[derive(Debug, PartialEq, PartialOrd, Eq, Ord, Clone)]
struct Card(u8, char);
impl Card {
fn new(card: &str) -> Option<Card> {
let value = match &card[0..card.len() - 1] {
"A" => 14,
"J" => 11,
"Q" => 12,
"K" => 13,
s => s.parse().ok().filter(|&x| x >= 2 && x <= 10)?,
};
let suite = card.chars().last().filter(|&s| s == 'H' || s == 'D' || s == 'S' || s == 'C')?;
Some(Card(value, suite))
}
}
#[test]
fn test_invalid_hand() {
assert!(winning_hands(&[""]).is_none());
assert!(winning_hands(&["4S 20S AS AH 2C"]).is_none());
assert!(winning_hands(&["4S 1S AS AH 2C"]).is_none());
assert!(winning_hands(&["4S 1S AH 2C"]).is_none());
assert!(winning_hands(&["4S 2S AS AH 2C"]).is_some());
assert!(winning_hands(&["4S 2s AS AH 2C"]).is_none());
assert!(winning_hands(&["4Z 2s AS AH 2C"]).is_none());
assert!(winning_hands(&["4SASAH2C10D"]).is_none());
}
[package]
edition = "2018"
name = "poker"
version = "1.1.0"
[dependencies]
itertools = "0.8.2"
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