Advent 2025 Day 5, Part 1 & 2

advent_of_code_2025/src/day5/mod.rs

@@ -0,0 +1,2 @@
+pub mod part1;
+pub mod part2;

advent_of_code_2025/src/day5/part1.rs

@@ -0,0 +1,23 @@
+pub fn solve(input: &str) {
+    let (fresh_ids, inventory) = input.split_once("\r\n\r\n").unwrap();
+
+    let fresh_ids = fresh_ids
+        .lines()
+        .map(|line| {
+            let (start, end) = line.split_once("-").unwrap();
+            (start.parse::<u64>().unwrap(), end.parse::<u64>().unwrap())
+        })
+        .collect::<Vec<_>>();
+
+    let inventory = inventory.lines().map(|line| line.parse::<u64>().unwrap()).collect::<Vec<_>>();
+
+    let mut fresh_count: u64 = 0;
+
+    for produce in inventory.iter() {
+        if fresh_ids.iter().any(|(start, end)| produce >= start && produce <= end) {
+            fresh_count += 1;
+        }
+    }
+
+    println!("fresh count: {fresh_count}");
+}

advent_of_code_2025/src/day5/part2.rs

@@ -0,0 +1,53 @@
+pub fn solve(input: &str) {
+    let (fresh_ids, _) = input.split_once("\r\n\r\n").unwrap();
+
+    let mut fresh_ids = fresh_ids
+        .lines()
+        .map(|line| {
+            let (start, end) = line.split_once("-").unwrap();
+            (start.parse::<u64>().unwrap(), end.parse::<u64>().unwrap())
+        })
+        .collect::<Vec<_>>();
+
+    let mut merged_fresh_ids: Vec<(u64, u64)> = Vec::new();
+
+    loop {
+        fresh_ids.sort_by(|lhs, rhs| lhs.0.cmp(&rhs.0));
+
+        let mut idx = 0usize;
+        while idx < fresh_ids.len() {
+            let first = fresh_ids[idx];
+
+            if idx == fresh_ids.len() - 1 {
+                merged_fresh_ids.push(first);
+                break;
+            }
+
+            let second = fresh_ids[idx + 1];
+
+            if first.1 >= second.0 || first.1 >= second.1 {
+                let merged = (first.0, first.1.max(second.1));
+                merged_fresh_ids.push(merged);
+                idx += 1;
+            } else {
+                merged_fresh_ids.push(first);
+            }
+
+            idx += 1;
+        }
+
+        if fresh_ids.len() == merged_fresh_ids.len() {
+            break;
+        }
+
+        fresh_ids = merged_fresh_ids.clone();
+        merged_fresh_ids.clear();
+    }
+
+    let mut number_of_fresh: u64 = 0;
+    for (start, end) in merged_fresh_ids {
+        number_of_fresh += (end + 1) - start;
+    }
+
+    println!("number of fresh: {number_of_fresh}");
+}

advent_of_code_2025/src/day5/test.txt

@@ -0,0 +1,11 @@
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32

advent_of_code_2025/src/main.rs

@@ -1,5 +1,5 @@
 use paste::paste;
 mod utility;
 
-solve_day!{4}
+solve_day!{5}
-// test_day!{4}
+// test_day!{5}