diff --git a/2018/loc.svg b/2018/loc.svg
index 67599d4..5cf04f8 100644
--- a/2018/loc.svg
+++ b/2018/loc.svg
@@ -32,10 +32,10 @@ z
+" id="me9ddb36467" style="stroke:#000000;stroke-width:0.8;"/>
-
+
@@ -71,7 +71,7 @@ z
-
+
@@ -110,7 +110,7 @@ z
-
+
@@ -139,7 +139,7 @@ z
-
+
@@ -153,7 +153,7 @@ z
-
+
@@ -193,7 +193,7 @@ z
-
+
@@ -286,10 +286,10 @@ z
+" id="mb89a9b780e" style="stroke:#000000;stroke-width:0.8;"/>
-
+
@@ -302,7 +302,7 @@ L -3.5 0
-
+
@@ -316,7 +316,7 @@ L -3.5 0
-
+
@@ -331,7 +331,7 @@ L -3.5 0
-
+
@@ -346,7 +346,7 @@ L -3.5 0
-
+
@@ -361,7 +361,7 @@ L -3.5 0
-
+
@@ -577,7 +577,7 @@ z
-
-
-
+
diff --git a/2018/src/common.rs b/2018/src/common.rs
index 38be760..cccba75 100644
--- a/2018/src/common.rs
+++ b/2018/src/common.rs
@@ -1,11 +1,36 @@
use std::collections::HashMap;
+use std::fmt::Debug;
use std::hash::Hash;
use std::io;
use std::io::Read;
-use std::str::FromStr;
use std::ops::Add;
use std::ops::Sub;
-use std::fmt::Debug;
+use std::str::FromStr;
+
+/// Utility trait for things representing coordinates.
+///
+/// This is implemented by default for any simple pair-tuple
+pub trait Point {
+ type CoordType;
+
+ /// Compute the manhattan distance between this and another.
+ ///
+ /// The distance will always be >= 0.
+ fn manhattan(self, other: Self) -> Self::CoordType;
+}
+
+impl Point for (T, T)
+ where T: Add + Sub + Copy + Ord
+{
+ type CoordType = T;
+
+ fn manhattan(self, other: Self) -> T {
+ let (xa, ya) = self;
+ let (xb, yb) = other;
+ xa.max(xb) + ya.max(yb) - xa.min(xb) - ya.min(yb)
+ }
+}
+
/// Apply Erathostenes's sieve to the supplied array
///
@@ -68,16 +93,6 @@ pub fn read_single_input(input: &mut Read) -> T
buf.trim().parse().unwrap()
}
-/// Compute the manhattan distance between two points of arbitrary type.
-pub fn manhattan_distance(a: (T, T), b: (T, T)) -> T
-where T: Copy + Add + Sub + Ord
-{
- let (xa, ya) = a;
- let (xb, yb) = b;
- xa.max(xb) + ya.max(yb) - xa.min(xb) - ya.min(yb)
-}
-
-
/// An interface to count elements in particular categories.
pub trait GroupingCount {
/// The type of the categories under inspection
diff --git a/2018/src/day06.rs b/2018/src/day06.rs
index d288822..0e50ced 100644
--- a/2018/src/day06.rs
+++ b/2018/src/day06.rs
@@ -4,7 +4,7 @@ use std::io::BufReader;
use std::io::Read;
use common::GroupingCount;
-use common::manhattan_distance;
+use common::Point;
use common::Solution;
type Coordinate = (usize, usize);
@@ -61,7 +61,7 @@ impl Day06 {
let mut cur_best = None;
for (i, point) in self.points.iter().enumerate() {
- let dist = manhattan_distance(*point, (x, y));
+ let dist = point.manhattan((x, y));
if dist < cur_dist {
cur_dist = dist;
cur_best = Some(i);
@@ -82,7 +82,7 @@ impl Day06 {
self.read_points(input);
self.range()
- .map(|x| self.points.iter().map(|y| manhattan_distance(x, *y)).sum::())
+ .map(|x| self.points.iter().map(|y| y.manhattan(x)).sum::())
.filter(|&x| x < limit)
.count()
}
diff --git a/2018/src/day15.rs b/2018/src/day15.rs
index 41fba57..41812fa 100644
--- a/2018/src/day15.rs
+++ b/2018/src/day15.rs
@@ -6,7 +6,7 @@ use std::io::BufRead;
use std::io::BufReader;
use std::io::Read;
-use common::manhattan_distance;
+use common::Point;
use common::Solution;
type Coordinate = (usize, usize);
@@ -122,7 +122,7 @@ impl Day15 {
let to_attack = self.units.iter()
.enumerate()
.filter(|(_, x)| x.faction != faction && x.is_alive())
- .filter(|(_, x)| manhattan_distance(x.pos, initial) == 1)
+ .filter(|(_, x)| x.pos.manhattan(initial) == 1)
.min_by(|&(_, a), &(_, b)| a.hp.cmp(&b.hp).then(a.pos.cmp(&b.pos)));
if let Some((index, _)) = to_attack {
diff --git a/2018/src/day22.rs b/2018/src/day22.rs
index 26911c3..7c356ca 100644
--- a/2018/src/day22.rs
+++ b/2018/src/day22.rs
@@ -5,7 +5,7 @@ use std::io::BufRead;
use std::io::BufReader;
use std::io::Read;
-use common::manhattan_distance;
+use common::Point;
use common::Solution;
type Coordinate = (usize, usize);
@@ -107,7 +107,7 @@ impl Solution for Day22 {
let mut visited: HashSet = HashSet::new();
let target_state = State { pos: target, climbing: false, torch: true };
- todo.push((Reverse(manhattan_distance((0, 0), target)), Reverse(0), State { pos: (0, 0), climbing: false, torch: true }));
+ todo.push((Reverse((0, 0).manhattan(target)), Reverse(0), State { pos: (0, 0), climbing: false, torch: true }));
while let Some((Reverse(approx), Reverse(dist), state)) = todo.pop() {
if visited.contains(&state) {
@@ -147,7 +147,7 @@ impl Solution for Day22 {
};
if !visited.contains(&new_state) && new_state.is_valid(table[yn][xn]) && (x == xn || y == yn) {
- todo.push((Reverse(dist + 1 + manhattan_distance(target, new_state.pos)), Reverse(dist + 1), new_state));
+ todo.push((Reverse(dist + 1 + target.manhattan(new_state.pos)), Reverse(dist + 1), new_state));
}
}
}