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|
use nom::{
bytes::complete::tag, character::complete::i32 as nom_i32, combinator::map, sequence::tuple,
IResult,
};
use std::fs;
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("inputs/day_17.txt")?;
let target = parse_target(&input).unwrap().1;
let max_y_throw = 0 - target.min_y - 1;
let max_height = max_y_throw * (max_y_throw + 1) / 2;
dbg!(max_height);
let min_y_throw = target.min_y;
let max_x_throw = target.max_x;
let min_x_throw = (2.0 * target.min_x as f32).sqrt() as i32;
let mut count = 0;
for x in min_x_throw..=max_x_throw {
for y in min_y_throw..=max_y_throw {
if simulate_throw(x, y, &target) {
count += 1;
}
}
}
dbg!(count);
Ok(())
}
fn simulate_throw(mut x_vel: i32, mut y_vel: i32, target: &TargetArea) -> bool {
let mut x_pos = 0;
let mut y_pos = 0;
loop {
x_pos += x_vel;
y_pos += y_vel;
if x_vel > 0 {
x_vel -= 1;
}
y_vel -= 1;
if x_pos >= target.min_x
&& x_pos <= target.max_x
&& y_pos >= target.min_y
&& y_pos <= target.max_y
{
return true;
}
if x_pos > target.max_x || y_pos < target.min_y {
return false;
}
}
}
#[derive(Debug)]
struct TargetArea {
min_x: i32,
max_x: i32,
min_y: i32,
max_y: i32,
}
fn parse_target(input: &str) -> IResult<&str, TargetArea> {
map(
tuple((
tag("target area: x="),
nom_i32,
tag(".."),
nom_i32,
tag(", y="),
nom_i32,
tag(".."),
nom_i32,
)),
|(_, min_x, _, max_x, _, min_y, _, max_y)| TargetArea {
min_x,
max_x,
min_y,
max_y,
},
)(input)
}
|
