day 22 part 2 solution

2023/src/bin/22.rs

@@ -1,7 +1,7 @@
 advent_of_code::solution!(22);
 
 use aoc_parse::{parser, prelude::*};
-use std::collections::{HashMap, HashSet};
+use std::collections::{HashMap, HashSet, VecDeque};
 
 #[derive(Clone, Copy, Debug, PartialOrd, Ord, Eq, PartialEq)]
 struct Coord {
@@ -26,12 +26,10 @@ impl Block {
     }
 
     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
     }
 }
@@ -77,13 +75,6 @@ fn drop_blocks(blocks: &[Block]) -> Vec<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);
@@ -111,7 +102,46 @@ pub fn part_one(input_str: &str) -> Option<usize> {
 }
 
 pub fn part_two(input_str: &str) -> Option<usize> {
-    None
+    let input = parse(input_str);
+    let btm = drop_blocks(&input);
+    let mut a: HashMap<usize, Vec<usize>> = HashMap::new();
+    for outside in btm.iter() {
+        let mut above: Vec<usize> = vec![];
+        for inside in btm.iter() {
+            if inside.above(&outside) {
+                above.push(inside.id);
+            }
+        }
+        a.insert(outside.id, above);
+    }
+    let mut result = 0;
+    let mut v: HashSet<usize> = HashSet::new();
+    let mut p: VecDeque<usize> = VecDeque::new();
+    for b in btm.iter() {
+        if b.one.z == 1 {
+            v.insert(b.id);
+            p.push_back(b.id);
+        }
+    }
+    for id in 1..=btm.len() {
+        let mut visited = v.clone();
+        let mut path = p.clone();
+        while let Some(next) = path.pop_front() {
+            if next == id {
+                continue;
+            }
+            if let Some(above) = a.get(&next) {
+                for &above_id in above {
+                    if !visited.contains(&above_id) {
+                        visited.insert(above_id);
+                        path.push_back(above_id);
+                    }
+                }
+            }
+        }
+        result += btm.len() - visited.len();
+    }
+    Some(result)
 }
 
 #[cfg(test)]
@@ -127,7 +157,7 @@ mod tests {
     #[test]
     fn test_part_two() {
         let result = part_two(&advent_of_code::template::read_file("examples", DAY));
-        assert_eq!(result, None);
+        assert_eq!(result, Some(7));
     }
 
     fn perform_test_intersect(