day 22 part 1 solution

2023/src/bin/22.rs

@@ -1,10 +1,116 @@
 advent_of_code::solution!(22);
 
-pub fn part_one(input: &str) -> Option<u32> {
-    None
+use aoc_parse::{parser, prelude::*};
+use std::collections::{HashMap, HashSet};
+
+#[derive(Clone, Copy, Debug, PartialOrd, Ord, Eq, PartialEq)]
+struct Coord {
+    z: usize,
+    x: usize,
+    y: usize,
 }
 
-pub fn part_two(input: &str) -> Option<u32> {
+#[derive(Debug, Clone, PartialOrd, Ord, Eq, PartialEq)]
+struct Block {
+    id: usize,
+    one: Coord,
+    two: Coord,
+}
+
+impl Block {
+    fn intersect_xy(&self, other: &Self) -> bool {
+        self.one.x <= other.two.x
+            && other.one.x <= self.two.x
+            && self.one.y <= other.two.y
+            && other.one.y <= self.two.y
+    }
+
+    fn below(&self, other: &Self) -> bool {
+        // self.id != other.id && self.intersect_xy(other) && self.two.z == other.one.z - 1
+        self.intersect_xy(other) && self.two.z == other.one.z - 1
+    }
+
+    fn above(&self, other: &Self) -> bool {
+        // self.id != other.id && self.intersect_xy(other) && self.one.z == other.two.z + 1
+        self.intersect_xy(other) && self.one.z == other.two.z + 1
+    }
+}
+
+fn parse(input: &str) -> Vec<Block> {
+    let p = parser!(lines(usize "," usize "," usize "~" usize "," usize "," usize));
+    let mut blocks = p
+        .parse(input)
+        .unwrap()
+        .iter()
+        .enumerate()
+        .map(|(index, r)| Block {
+            id: index + 1,
+            one: Coord {
+                z: r.2,
+                x: r.0,
+                y: r.1,
+            },
+            two: Coord {
+                z: r.5,
+                x: r.3,
+                y: r.4,
+            },
+        })
+        .collect::<Vec<_>>();
+    blocks.sort_by_key(|b| b.one);
+    blocks
+}
+
+fn drop_blocks(blocks: &[Block]) -> Vec<Block> {
+    let mut btm: Vec<Block> = Vec::with_capacity(blocks.len());
+    for b in blocks.iter() {
+        let mut block = b.clone();
+        for _i in 1..b.one.z {
+            if let Some(_below) = btm.iter().find(|d| d.below(&block)) {
+                break;
+            }
+            block.one.z -= 1;
+            block.two.z -= 1;
+        }
+        btm.push(block);
+    }
+    btm
+}
+
+fn pyprint(b: &Block) {
+    println!(
+        "(({}, {}, {}), ({}, {}, {}))",
+        b.one.x, b.one.y, b.one.z, b.two.x, b.two.y, b.two.z
+    );
+}
+
+pub fn part_one(input_str: &str) -> Option<usize> {
+    let input = parse(input_str);
+    let btm = drop_blocks(&input);
+    let mut b: HashMap<usize, Vec<usize>> = HashMap::new();
+    for outside in btm.iter() {
+        let mut below: Vec<usize> = vec![];
+        for inside in btm.iter() {
+            if inside.below(&outside) {
+                below.push(inside.id);
+            }
+        }
+        b.insert(outside.id, below);
+    }
+    let mut s: HashSet<usize> = HashSet::new();
+    for id in 1..=btm.len() {
+        if let Some(below) = b.get(&id) {
+            if below.len() == 1 {
+                for &x in below {
+                    s.insert(x);
+                }
+            }
+        }
+    }
+    Some(btm.len() - s.len())
+}
+
+pub fn part_two(input_str: &str) -> Option<usize> {
     None
 }
 
@@ -15,7 +121,7 @@ mod tests {
     #[test]
     fn test_part_one() {
         let result = part_one(&advent_of_code::template::read_file("examples", DAY));
-        assert_eq!(result, None);
+        assert_eq!(result, Some(5));
     }
 
     #[test]
@@ -23,4 +129,62 @@ mod tests {
         let result = part_two(&advent_of_code::template::read_file("examples", DAY));
         assert_eq!(result, None);
     }
+
+    fn perform_test_intersect(
+        one: &(usize, usize, usize, usize, usize, usize),
+        two: &(usize, usize, usize, usize, usize, usize),
+        res: bool,
+    ) {
+        let b1 = Block {
+            id: 1,
+            one: Coord {
+                x: one.0,
+                y: one.1,
+                z: one.2,
+            },
+            two: Coord {
+                x: one.3,
+                y: one.4,
+                z: one.5,
+            },
+        };
+        let b2 = Block {
+            id: 2,
+            one: Coord {
+                x: two.0,
+                y: two.1,
+                z: two.2,
+            },
+            two: Coord {
+                x: two.3,
+                y: two.4,
+                z: two.5,
+            },
+        };
+        assert_eq!(b1.intersect_xy(&b2), res);
+    }
+
+    #[test]
+    fn test_intersect_xy() {
+        let false_coords = [
+            [(0, 0, 1, 0, 0, 1), (1, 0, 1, 4, 0, 1)],
+            [(0, 0, 1, 0, 0, 1), (0, 1, 1, 0, 4, 1)],
+            [(0, 0, 1, 10, 0, 1), (1, 1, 1, 1, 1, 1)],
+            [(0, 0, 1, 10, 0, 1), (1, 1, 1, 1, 10, 1)],
+        ];
+        for row in false_coords.iter() {
+            let one = row[0];
+            let two = row[1];
+            perform_test_intersect(&one, &two, false);
+        }
+        let true_coords = [
+            [(0, 0, 1, 0, 0, 1), (0, 0, 1, 4, 0, 1)],
+            [(0, 0, 1, 10, 0, 1), (5, 0, 1, 5, 5, 1)],
+        ];
+        for row in true_coords.iter() {
+            let one = row[0];
+            let two = row[1];
+            perform_test_intersect(&one, &two, true);
+        }
+    }
 }