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use std::collections::HashSet;
fn solve_part_one(input: &str) -> i32 {
let mut seen = HashSet::new();
let numbers: Vec<i32> = input
.lines()
.map(|line| line.trim().parse().unwrap())
.collect();
for &number in &numbers {
let complement = 2020 - number;
if seen.contains(&complement) {
return number * complement;
}
seen.insert(number);
}
panic!("No two numbers sum to 2020!");
}
fn solve_part_two(input: &str) -> i32 {
let numbers: Vec<i32> = input
.lines()
.map(|line| line.trim().parse().unwrap())
.collect();
for (i, &first) in numbers.iter().enumerate() {
let mut seen = HashSet::new();
let target_sum = 2020 - first;
for &second in &numbers[i + 1..] {
let complement = target_sum - second;
if seen.contains(&complement) {
return first * second * complement;
}
seen.insert(second);
}
}
panic!("No three numbers sum to 2020!");
}
fn main() {
let test = include_str!("../input/day_1.test");
let prod = include_str!("../input/day_1.prod");
println!("Test_1: {}", solve_part_one(test));
println!("Prod_1: {}", solve_part_one(prod));
println!("Test_2: {}", solve_part_two(test));
println!("Prod_2: {}", solve_part_two(prod));
}
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