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use std::collections::HashMap;
use std::io::{self, Read};
fn frequencies(chars: &[char]) -> HashMap<char, u32> {
let mut map = HashMap::new();
for &ch in chars {
*map.entry(ch).or_insert(0) += 1;
}
map
}
fn solve1(input: &str) -> String {
let len = input.find('\n').unwrap_or(input.len());
let mut columns = vec![Vec::new(); len];
for line in input.lines() {
for (i, ch) in line.chars().enumerate() {
columns[i].push(ch);
}
}
columns.into_iter()
.map(|column| frequencies(&column))
.map(IntoIterator::into_iter)
.map(|iter| iter.max_by_key(|&(_, v)| v))
.map(Option::unwrap)
.map(|(ch, _)| ch)
.collect()
}
fn solve2(input: &str) -> String {
let len = input.find('\n').unwrap_or(input.len());
let mut columns = vec![Vec::new(); len];
for line in input.lines() {
for (i, ch) in line.chars().enumerate() {
columns[i].push(ch);
}
}
columns.into_iter()
.map(|column| frequencies(&column))
.map(IntoIterator::into_iter)
.map(|iter| iter.min_by_key(|&(_, v)| v))
.map(Option::unwrap)
.map(|(ch, _)| ch)
.collect()
}
fn main() {
let mut input = String::new();
io::stdin().read_to_string(&mut input).unwrap();
println!("Part 1: {}", solve1(&input));
println!("Part 2: {}", solve2(&input));
}
#[cfg(test)]
const TEST_INPUT: &'static str = "
eedadn
drvtee
eandsr
raavrd
atevrs
tsrnev
sdttsa
rasrtv
nssdts
ntnada
svetve
tesnvt
vntsnd
vrdear
dvrsen
enarar
";
#[test]
fn part1() {
assert_eq!("easter", solve1(TEST_INPUT.trim()));
}
#[test]
fn part2() {
assert_eq!("advent", solve2(TEST_INPUT.trim()));
}
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