决定尝试有关 Exercism 的字母数学问题，并使用蛮力但同时的方法，我以相当有效的方式解决了除了最终测试之外的所有问题。我无法弄清楚为什么最终测试失败了，因为唯一额外的复杂性是加数的数量。我认为这是我如何处理列的进位数字的问题，但这也应该让我在其他测试中绊倒。我的代码：
use combination::combine::*;
use combination::permutate::*;
use rayon::prelude::*;
use std::collections::HashMap;
use std::collections::HashSet;
const DIGITS: [u8; 10] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
pub fn solve(input: &str) -> Option<HashMap<char, u8>> {
let alphametic = Alphametic::from_str(input);
alphametic.brute_force()
}
#[derive(Debug, Clone)]
struct Alphametic {
firsts: HashSet<char>,
columns: Vec<Vec<char>>,
keys: HashSet<char>,
}
impl Alphametic {
fn from_str(input: &str) -> Self {
let mut firsts = HashSet::new();
let terms = input
.split_whitespace()
.rev()
.filter(|&sub| sub != "+" && sub != "==")
.map(|sub| {
firsts.insert(sub.chars().next().unwrap());
sub
})
.map(|sub| sub.chars().rev().collect::<Vec<char>>())
.collect::<Vec<Vec<char>>>();
let max_cols = terms[0].len();
let mut columns = vec![];
for i in 0..max_cols {
columns.push(
terms
.iter()
.filter(|term| !(term.len() <= i))
.map(|term| term[i])
.collect::<Vec<char>>(),
)
}
let keys = terms
.iter()
.flatten()
.map(|&c| c)
.collect::<HashSet<char>>();
Alphametic {
firsts,
columns,
keys,
}
}
fn brute_force(&self) -> Option<HashMap<char, u8>> {
let combo_len = self.keys.len();
let combos = combine_vec(&DIGITS.to_vec(), combo_len);
if let Some(soln) = combos
.par_iter()
.map(|combo| {
let perms = permutate_vec(&combo);
perms
.par_iter()
.map(|perm| self.to_guess(&perm))
.filter(|guess| self.no_leading_zeros(guess))
.find_first(|guess| self.guess_columns(guess.clone(), 0, 0).is_some())
})
.find_first(|x| x.is_some())
{
soln
} else {
None
}
}
fn no_leading_zeros(&self, guess: &HashMap<char, u8>) -> bool {
self.firsts.iter().all(|c| guess.get(c).unwrap_or(&0) > &0)
}
fn guess_columns(
&self,
guess: HashMap<char, u8>,
column: usize,
carry: u8,
) -> Option<HashMap<char, u8>> {
if column >= self.columns.len() {
Some(guess)
} else {
let col = &self.columns[column];
let sum = *guess.get(&col[0]).unwrap();
let addition = col[1..].iter().map(|c| guess.get(c).unwrap()).sum::<u8>() + carry;
if sum == addition % 10 {
self.guess_columns(guess, column + 1, addition / 10)
} else {
None
}
}
}
fn to_guess(&self, perm: &&Vec<u8>) -> HashMap<char, u8> {
self.keys
.iter()
.zip(*perm)
.map(|(k, v)| (*k, *v))
.collect::<HashMap<char, u8>>()
}
}
测试输入：
fn test_puzzle_with_ten_letters_and_199_addends() {
assert_alphametic_solution_eq(
"THIS + A + FIRE + THEREFORE + FOR + ALL + HISTORIES + I + TELL + A + TALE + THAT + FALSIFIES + ITS + TITLE + TIS + A + LIE + THE + TALE + OF + THE + LAST + FIRE + HORSES + LATE + AFTER + THE + FIRST + FATHERS + FORESEE + THE + HORRORS + THE + LAST + FREE + TROLL + TERRIFIES + THE + HORSES + OF + FIRE + THE + TROLL + RESTS + AT + THE + HOLE + OF + LOSSES + IT + IS + THERE + THAT + SHE + STORES + ROLES + OF + LEATHERS + AFTER + SHE + SATISFIES + HER + HATE + OFF + THOSE + FEARS + A + TASTE + RISES + AS + SHE + HEARS + THE + LEAST + FAR + HORSE + THOSE + FAST + HORSES + THAT + FIRST + HEAR + THE + TROLL + FLEE + OFF + TO + THE + FOREST + THE + HORSES + THAT + ALERTS + RAISE + THE + STARES + OF + THE + OTHERS + AS + THE + TROLL + ASSAILS + AT + THE + TOTAL + SHIFT + HER + TEETH + TEAR + HOOF + OFF + TORSO + AS + THE + LAST + HORSE + FORFEITS + ITS + LIFE + THE + FIRST + FATHERS + HEAR + OF + THE + HORRORS + THEIR + FEARS + THAT + THE + FIRES + FOR + THEIR + FEASTS + ARREST + AS + THE + FIRST + FATHERS + RESETTLE + THE + LAST + OF + THE + FIRE + HORSES + THE + LAST + TROLL + HARASSES + THE + FOREST + HEART + FREE + AT + LAST + OF + THE + LAST + TROLL + ALL + OFFER + THEIR + FIRE + HEAT + TO + THE + ASSISTERS + FAR + OFF + THE + TROLL + FASTS + ITS + LIFE + SHORTER + AS + STARS + RISE + THE + HORSES + REST + SAFE + AFTER + ALL + SHARE + HOT + FISH + AS + THEIR + AFFILIATES + TAILOR + A + ROOFS + FOR + THEIR + SAFE == FORTRESSES",
&[
('A', 1),
('E', 0),
('F', 5),
('H', 8),
('I', 7),
('L', 2),
('O', 6),
('R', 3),
('S', 4),
('T', 9),
],
);
我知道正在生成正确的猜测，因为如果插入对哈希图的条件检查，则测试期望它成功。
关于如何调试的任何提示？