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day11 part2 fast

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This commit is contained in:
Johannes Schaefer
2018-12-11 16:02:22 +01:00
parent fc328d82af
commit 54103e8fa6
2 changed files with 63 additions and 2 deletions
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2
src/main.rs
View File

@@ -1,4 +1,4 @@
fn main() {
// aoc_2018::tasks::day11::task1();
aoc_2018::tasks::day11::task2();
aoc_2018::tasks::day11::task2_fast();
}

63
src/tasks/day11.rs
View File

@@ -19,6 +19,17 @@ pub fn task1() {
pub fn task2() {
let serial = 6392;
let mut values: Vec<Vec<i32>> = Vec::with_capacity(301);
for x in 0..=300 {
let mut v: Vec<i32> = Vec::with_capacity(301);
for y in 0..=300 {
v.push(fuel_level(x, y, serial));
}
values.push(v);
}
let values = &values;
let result = (1..300)
.map(|square_size| {
let result = (1..=300 - square_size)
@@ -27,7 +38,7 @@ pub fn task2() {
let power: i32 = (x..x + square_size)
.map(|x| {
(y..y + square_size)
.map(move |y| fuel_level(x, y, serial))
.map(move |y| values[x as usize][y as usize])
.sum::<i32>()
})
.sum();
@@ -41,6 +52,56 @@ pub fn task2() {
println!("{:?}", result);
}
pub fn task2_fast() {
let serial = 6392;
let mut cache: Vec<Vec<i32>> = Vec::with_capacity(301);
for x in 0 as usize..=300 {
let mut v: Vec<i32> = Vec::with_capacity(301);
for y in 0 as usize..=300 {
if x == 0 || y == 0 {
v.push(0);
} else {
v.push(
fuel_level(x as i32, y as i32, serial) + v[v.len() - 1] + cache[x - 1][y]
- cache[x - 1][y - 1],
)
}
}
cache.push(v);
}
let values = &cache;
for x in 0 as usize..=300 {
for y in 0 as usize..=300 {
if x != 0 && y != 0 {
let cached = area_sum(&values, x, y, 1);
let calc = fuel_level(x as i32, y as i32, serial);
//println!("{},{}: {} ({})", x, y, values[x][y], calc);
assert_eq!(calc, cached);
}
}
}
let result = (1..=300)
.map(|square_size| {
let result = (1..=301 - square_size)
.flat_map(|x: usize| (1..=301 - square_size).map(move |y: usize| (x, y)))
.map(|(x, y)| (x, y, area_sum(&values, x, y, square_size)))
.max_by_key(|(_, _, value)| *value)
.unwrap();
(result.0, result.1, result.2, square_size)
})
.max_by_key(|result| result.2);
println!("{:?}", result);
}
fn area_sum(values: &Vec<Vec<i32>>, x: usize, y: usize, length: usize) -> i32 {
values[x + length - 1][y + length - 1] + values[x - 1][y - 1]
- values[x - 1][y + length - 1]
- values[x + length - 1][y - 1]
}
fn fuel_level(x: i32, y: i32, serial: i32) -> i32 {
let rack_id = x + 10;
let mut power = rack_id * y;