advent-of-code/2019/02/day2.rs

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Rust
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use std::io;
use std::io::BufRead;
pub fn main() {
let input: Vec<usize> = io::stdin()
.lock()
.lines()
.next()
.unwrap()
.unwrap()
.split(',')
.map(|n| n.parse().unwrap())
.collect();
println!("Part 1: {}", execute(&mut input.clone(), 12, 2));
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let part2_target = 19690720;
let part2 = (1..99)
.flat_map(|x| (1..99).map(move |y| (x, y)))
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.filter(|(x, y)| execute(&mut input.clone(), *x, *y) == part2_target)
.map(|(x, y)| x * 100 + y)
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.next()
.unwrap();
println!("Part 2: {}", part2);
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}
fn execute(input: &mut Vec<usize>, p1: usize, p2: usize) -> usize {
input[1] = p1;
input[2] = p2;
for i in (0..).step_by(4) {
let opcode = input[i];
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let first = input[i + 1];
let second = input[i + 2];
let target = input[i + 3];
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match opcode {
1 => input[target] = input[first] + input[second],
2 => input[target] = input[first] * input[second],
99 => break,
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_ => unreachable!("Invalid opcode"),
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}
}
input[0]
}