day5: reimplement in a sane, fast way

5/Cargo.lock

@@ -14,45 +14,13 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
-[[package]]
-name = "crossbeam-deque"
-version = "0.8.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ce6fd6f855243022dcecf8702fef0c297d4338e226845fe067f6341ad9fa0cef"
-dependencies = [
- "cfg-if",
- "crossbeam-epoch",
- "crossbeam-utils",
-]
-
-[[package]]
-name = "crossbeam-epoch"
-version = "0.9.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae211234986c545741a7dc064309f67ee1e5ad243d0e48335adc0484d960bcc7"
-dependencies = [
- "autocfg",
- "cfg-if",
- "crossbeam-utils",
- "memoffset",
- "scopeguard",
-]
-
-[[package]]
-name = "crossbeam-utils"
-version = "0.8.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a22b2d63d4d1dc0b7f1b6b2747dd0088008a9be28b6ddf0b1e7d335e3037294"
-dependencies = [
- "cfg-if",
-]
-
 [[package]]
 name = "day5"
 version = "0.1.0"
 dependencies = [
  "itertools",
- "rayon",
+ "num",
+ "test-case",
 ]
 
 [[package]]
@@ -71,36 +39,145 @@ dependencies = [
 ]
 
 [[package]]
-name = "memoffset"
+name = "num"
-version = "0.9.0"
+version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a634b1c61a95585bd15607c6ab0c4e5b226e695ff2800ba0cdccddf208c406c"
+checksum = "b05180d69e3da0e530ba2a1dae5110317e49e3b7f3d41be227dc5f92e49ee7af"
+dependencies = [
+ "num-bigint",
+ "num-complex",
+ "num-integer",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+]
+
+[[package]]
+name = "num-bigint"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "608e7659b5c3d7cba262d894801b9ec9d00de989e8a82bd4bef91d08da45cdc0"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-complex"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ba157ca0885411de85d6ca030ba7e2a83a28636056c7c699b07c8b6f7383214"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "225d3389fb3509a24c93f5c29eb6bde2586b98d9f016636dff58d7c6f7569cd9"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-iter"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d03e6c028c5dc5cac6e2dec0efda81fc887605bb3d884578bb6d6bf7514e252"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0638a1c9d0a3c0914158145bc76cff373a75a627e6ecbfb71cbe6f453a5a19b0"
+dependencies = [
+ "autocfg",
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
 dependencies = [
  "autocfg",
 ]
 
 [[package]]
-name = "rayon"
+name = "proc-macro2"
-version = "1.8.0"
+version = "1.0.70"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c27db03db7734835b3f53954b534c91069375ce6ccaa2e065441e07d9b6cdb1"
+checksum = "39278fbbf5fb4f646ce651690877f89d1c5811a3d4acb27700c1cb3cdb78fd3b"
 dependencies = [
- "either",
+ "unicode-ident",
- "rayon-core",
 ]
 
 [[package]]
-name = "rayon-core"
+name = "quote"
-version = "1.12.0"
+version = "1.0.33"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5ce3fb6ad83f861aac485e76e1985cd109d9a3713802152be56c3b1f0e0658ed"
+checksum = "5267fca4496028628a95160fc423a33e8b2e6af8a5302579e322e4b520293cae"
 dependencies = [
- "crossbeam-deque",
+ "proc-macro2",
- "crossbeam-utils",
 ]
 
 [[package]]
-name = "scopeguard"
+name = "syn"
-version = "1.2.0"
+version = "2.0.41"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
+checksum = "44c8b28c477cc3bf0e7966561e3460130e1255f7a1cf71931075f1c5e7a7e269"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "test-case"
+version = "3.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb2550dd13afcd286853192af8601920d959b14c401fcece38071d53bf0768a8"
+dependencies = [
+ "test-case-macros",
+]
+
+[[package]]
+name = "test-case-core"
+version = "3.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "adcb7fd841cd518e279be3d5a3eb0636409487998a4aff22f3de87b81e88384f"
+dependencies = [
+ "cfg-if",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "test-case-macros"
+version = "3.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c89e72a01ed4c579669add59014b9a524d609c0c88c6a585ce37485879f6ffb"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "test-case-core",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"

5/Cargo.toml

@@ -7,4 +7,5 @@ edition = "2021"
 
 [dependencies]
 itertools = "0.12.0"
-rayon = "1.8.0"
+num = "0.4.1"
+test-case = "3.3.1"

5/src/main.rs

@@ -153,16 +153,16 @@ fn main() {
 
 #[derive(Debug)]
 struct AlmanacMapping {
-    source_range: Range<u64>,
+    source_range: Range<i64>,
-    dest_range: Range<u64>,
+    dest_range: Range<i64>,
 }
 
 impl From<&str> for AlmanacMapping {
     fn from(s: &str) -> Self {
         let s_nums: Vec<_> = s.split_whitespace().take(3).collect();
-        let length: u64 = s_nums[2].parse().unwrap();
+        let length: i64 = s_nums[2].parse().unwrap();
-        let source_start: u64 = s_nums[1].parse().unwrap();
+        let source_start: i64 = s_nums[1].parse().unwrap();
-        let dest_start: u64 = s_nums[0].parse().unwrap();
+        let dest_start: i64 = s_nums[0].parse().unwrap();
         AlmanacMapping {
             source_range: source_start..source_start + length,
             dest_range: dest_start..dest_start + length,
@@ -171,7 +171,7 @@ impl From<&str> for AlmanacMapping {
 }
 
 impl AlmanacMapping {
-    fn lookup(&self, key: u64) -> Option<u64> {
+    fn lookup(&self, key: i64) -> Option<i64> {
         if self.source_range.contains(&key) {
             Some(self.dest_range.start + (key - self.source_range.start))
         } else {
@@ -186,13 +186,74 @@ struct AlmanacMappingTable {
     mappings: Vec<AlmanacMapping>,
 }
 
+fn range_overlap<T: num::Num + Ord + Copy>(r1: &Range<T>, r2: &Range<T>) -> Option<Range<T>> {
+    let new_start = std::cmp::max(r1.start, r2.start);
+    let new_end = std::cmp::min(r1.end - T::one(), r2.end - T::one());
+
+    if new_start <= std::cmp::min(r1.end - T::one(), r2.end - T::one())
+        && new_end >= std::cmp::max(r1.start, r2.start)
+    {
+        Some(new_start..new_end + T::one())
+    } else {
+        None
+    }
+}
+
+fn range_exclude<T: num::Num + Ord + Copy>(keep: &Range<T>, exclude: &Range<T>) -> Vec<Range<T>> {
+    let mut residual = Vec::new();
+    if let Some(overlap) = range_overlap(keep, exclude) {
+        if keep.start < overlap.start {
+            residual.push(keep.start..overlap.start);
+        }
+        if keep.end > overlap.end {
+            residual.push(overlap.end..keep.end);
+        }
+    } else {
+        residual.push(keep.clone());
+    }
+    residual
+}
+
 impl AlmanacMappingTable {
-    fn lookup(&self, key: u64) -> u64 {
+    fn lookup(&self, key: i64) -> i64 {
         self.mappings
             .iter()
             .find_map(|map| map.lookup(key))
             .unwrap_or(key)
     }
+    fn lookup_ranges(&self, ranges: Vec<Range<i64>>) -> Vec<Range<i64>> {
+        ranges
+            .iter()
+            .flat_map(|range| self.lookup_range(range))
+            .collect()
+    }
+    fn lookup_range(&self, range: &Range<i64>) -> Vec<Range<i64>> {
+        let mut residual = vec![range.clone()];
+        let mut resolved_mappings = Vec::new();
+
+        for map in &self.mappings {
+            let mut local_residual = Vec::new();
+            for range in residual.into_iter() {
+                if let Some(overlap) = range_overlap(&range, &map.source_range) {
+                    let dest_start_idx = overlap.start - map.source_range.start;
+                    let length = overlap.end.saturating_sub(overlap.start);
+                    resolved_mappings.push(
+                        (map.dest_range.start + dest_start_idx)
+                            ..(map.dest_range.start + dest_start_idx + length),
+                    );
+                    local_residual.extend_from_slice(&range_exclude(&range, &overlap));
+                } else {
+                    local_residual.push(range);
+                }
+            }
+            residual = local_residual;
+        }
+
+        // unresolved maps map 1:1
+        resolved_mappings.extend_from_slice(&residual);
+
+        resolved_mappings
+    }
 }
 
 impl<T: BufRead> From<&mut Lines<T>> for AlmanacMappingTable {
@@ -218,7 +279,7 @@ impl<T: BufRead> From<&mut Lines<T>> for AlmanacMappingTable {
 
 #[derive(Debug)]
 struct Almanac {
-    seeds: Vec<u64>,
+    seeds: Vec<i64>,
     seed_to_soil: AlmanacMappingTable,
     soil_to_fertilizer: AlmanacMappingTable,
     fertilizer_to_water: AlmanacMappingTable,
@@ -231,7 +292,7 @@ struct Almanac {
 impl<T: BufRead> From<Lines<T>> for Almanac {
     fn from(mut lines: Lines<T>) -> Self {
         let seeds_s = lines.next().unwrap().unwrap();
-        let seeds: Vec<u64> = seeds_s
+        let seeds: Vec<i64> = seeds_s
             .split_once(": ")
             .unwrap()
             .1
@@ -254,7 +315,7 @@ impl<T: BufRead> From<Lines<T>> for Almanac {
 }
 
 impl Almanac {
-    fn lookup(&self, seed_id: u64) -> u64 {
+    fn lookup(&self, seed_id: i64) -> i64 {
         self.humidity_to_location.lookup(
             self.temperature_to_humidity.lookup(
                 self.light_to_temperature.lookup(
@@ -268,6 +329,20 @@ impl Almanac {
             ),
         )
     }
+    fn lookup_range(&self, range: Range<i64>) -> Vec<Range<i64>> {
+        self.humidity_to_location.lookup_ranges(
+            self.temperature_to_humidity.lookup_ranges(
+                self.light_to_temperature.lookup_ranges(
+                    self.water_to_light.lookup_ranges(
+                        self.fertilizer_to_water.lookup_ranges(
+                            self.soil_to_fertilizer
+                                .lookup_ranges(self.seed_to_soil.lookup_ranges(vec![range])),
+                        ),
+                    ),
+                ),
+            ),
+        )
+    }
 }
 
 // PROBLEM 1 solution
@@ -287,7 +362,7 @@ impl Almanac {
 
 // What is the lowest location number that corresponds to any of the initial seed numbers?
 
-fn problem1_lowest_location(almanac: &Almanac) -> u64 {
+fn problem1_lowest_location(almanac: &Almanac) -> i64 {
     almanac
         .seeds
         .iter()
@@ -296,7 +371,7 @@ fn problem1_lowest_location(almanac: &Almanac) -> u64 {
         .unwrap()
 }
 
-fn problem1<T: BufRead>(input: Lines<T>) -> u64 {
+fn problem1<T: BufRead>(input: Lines<T>) -> i64 {
     let almanac = Almanac::from(input);
     problem1_lowest_location(&almanac)
 }
@@ -327,33 +402,40 @@ fn problem1<T: BufRead>(input: Lines<T>) -> u64 {
 // the almanac. What is the lowest location number that corresponds to any of the
 // initial seed numbers?
 
-fn problem2_lowest_location(almanac: &Almanac) -> u64 {
+fn problem2_lowest_location(almanac: &Almanac) -> i64 {
     let seed_ranges = almanac
         .seeds
         .iter()
         .tuples()
         .map(|(range_start, length)| *range_start..*range_start + *length);
 
-    seed_ranges
+    // seed_ranges
-        .map(|range| {
+    //     .map(|range| {
-            range
+    //         range
-                .into_par_iter()
+    //             .into_par_iter()
-                .map(|x| almanac.lookup(x))
+    //             .map(|x| almanac.lookup(x))
-                .min()
+    //             .min()
-                .unwrap()
+    //             .unwrap()
-        })
+    //     })
-        .min()
+    //     .min()
-        .unwrap()
+    //     .unwrap()
+    let ranges = seed_ranges
+        .flat_map(|range| almanac.lookup_range(range))
+        .collect_vec();
+
+    ranges.iter().map(|range| range.start).min().unwrap()
 }
 
-fn problem2<T: BufRead>(input: Lines<T>) -> u64 {
+fn problem2<T: BufRead>(input: Lines<T>) -> i64 {
     let almanac = Almanac::from(input);
     problem2_lowest_location(&almanac)
 }
 
 #[cfg(test)]
 mod tests {
+    use num::Num;
     use std::io::{BufRead, Cursor};
+    use test_case::test_case;
 
     use crate::*;
 
@@ -413,6 +495,18 @@ humidity-to-location map:
         assert_eq!(a.lookup(79), 82);
     }
 
+    #[test_case(0..5, 2..4, Some(2..4) ; "one range overlaps completely")]
+    #[test_case(0..5, 2..10, Some(2..5) ; "one range overlaps from below")]
+    #[test_case(0..5, 5..10, None ; "no overlap, touching")]
+    #[test_case(0..5, 6..10, None ; "no overlap, disjoint")]
+    fn test_range_overlap<T: Num + Copy + Ord + std::fmt::Debug>(
+        r1: Range<T>,
+        r2: Range<T>,
+        expected: Option<Range<T>>,
+    ) {
+        assert_eq!(range_overlap(&r1, &r2), expected);
+    }
+
     #[test]
     fn test_problem1_example() {
         let c = Cursor::new(EXAMPLE_ALMANAC);