commit e8fb670ee5bcbb21f4bcb3dbb63aec89f769aac5
Author: Thomas de Gruijter <thomasdegruijter@pm.me>
Date:   Tue Dec 2 18:45:40 2025 +0100

    day 2

diff --git a/past-solutions/2-1.rs b/past-solutions/2-1.rs
new file mode 100644
index 0000000..7b56a01
--- /dev/null
+++ b/past-solutions/2-1.rs
@@ -0,0 +1,120 @@
+use std::io::Read;
+use std::iter;
+use std::num::{NonZero, NonZeroU32};
+
+fn main() {
+    let mut problem = parse_problem();
+
+    println!("Parsed problem: {:?}", problem);
+
+    println!("Count in total: {}", compute_problem(&mut problem))
+}
+
+#[derive(Debug)]
+struct Problem{
+    ranges: Vec<(u64, u64)>
+}
+
+#[derive(Debug)]
+struct CleanedProblem{
+    ranges: Vec<(u64, u64, NonZeroU32)>
+}
+
+fn parse_problem() -> Problem {
+    let mut input = String::new();
+    std::io::stdin().read_to_string(&mut input).expect("Failed to read input");
+
+    let ranges = input.split(',').
+        map(|x| x.split_once('-').expect("dash in there"))
+        .map(|x| (x.0.parse::<u64>().expect("Parse error on 0"), x.1.parse::<u64>().expect("Parse error on 1")))
+        .collect::<Vec<_>>();
+
+    return Problem{
+        ranges,
+    };
+}
+
+fn compute_problem(problem: &mut Problem) -> u64 {
+    //Potentialy ensure it is not overlapping
+    let problem = clean_problem(problem);
+
+    println!("Cleaned problem: {:?}", problem);
+
+    let count = problem.ranges.iter().map(|range| compute_range(range.0, range.1)).sum::<u64>();
+
+    return count;
+}
+
+fn clean_problem(problem: &Problem) -> CleanedProblem {
+    let new_ranges = problem.ranges.iter().map(|(lower, upper)|{
+        if (upper < lower){
+            return vec![]
+        }
+
+        let digitCountU = count_digits(*upper);
+        let digitCountL = count_digits(*lower);
+
+        if (digitCountL == digitCountU){
+            return vec![(*lower, *upper, digitCountU)];
+        }
+
+        let lowestOfDegree = lowestOfDegree(digitCountU);
+
+        return vec![(*lower, lowestOfDegree-1, digitCountL), (lowestOfDegree, *upper, digitCountU)];
+    }).flatten().collect::<Vec<_>>();
+
+  return CleanedProblem{ranges: new_ranges};
+}
+
+fn lowestOfDegree(degree : NonZeroU32) -> u64{
+    10u64.pow(degree.get() - 1)
+}
+
+fn compute_range(lower_bound: u64, upper_bound: u64) -> u64 {
+    assert!(lower_bound > 0 && upper_bound > 0);
+    assert!(upper_bound > lower_bound);
+    assert!(count_digits(upper_bound) == count_digits(lower_bound));
+
+    let digitCount = count_digits(upper_bound);
+
+    if digitCount.get() % 2 != 0{
+        return 0;
+    }
+
+
+    let halfDigitCount = NonZeroU32::new(digitCount.get() / 2).unwrap();
+
+
+
+    let mut half = (lower_bound / 10u64.pow(halfDigitCount.get())).min(lower_bound % 10u64.pow(halfDigitCount.get()));
+    let mut count = 0;
+
+    loop{
+        let whole = combine_numbers(half, halfDigitCount);
+        if whole >= lower_bound && whole <= upper_bound{
+            count += whole;
+        }else if whole > upper_bound{
+            break;
+        }
+
+        half += 1;
+    }
+
+    return count;
+}
+
+fn count_digits(mut n : u64) -> NonZeroU32{
+    assert!(n > 0);
+    let mut count = 0u64;
+
+    while (n != 0){
+        n = n / 10;
+        count +=1 ;
+    }
+
+    return unsafe{NonZeroU32::new_unchecked(count as u32)};
+}
+
+fn combine_numbers(half : u64, degree : NonZeroU32) -> u64 {
+    return half + half * 10u64.pow(degree.get() as u32)
+}
\ No newline at end of file
diff --git a/past-solutions/2-2.rs b/past-solutions/2-2.rs
new file mode 100644
index 0000000..9d08ac8
--- /dev/null
+++ b/past-solutions/2-2.rs
@@ -0,0 +1,114 @@
+use std::collections::HashSet;
+use std::io::Read;
+use std::iter;
+use std::num::{NonZero, NonZeroU32, NonZeroU64};
+use rayon::prelude::*;
+
+fn main() {
+    let mut problem = parse_problem();
+
+    println!("Count in total: {}", compute_problem(&mut problem))
+}
+
+#[derive(Debug)]
+struct Problem{
+    ranges: Vec<(u64, u64)>
+}
+
+#[derive(Debug)]
+struct CleanedProblem{
+    ranges: Vec<(u64, u64, NonZeroU32)>
+}
+
+fn parse_problem() -> Problem {
+    let mut input = String::new();
+    std::io::stdin().read_to_string(&mut input).expect("Failed to read input");
+
+    let ranges = input.split(',').
+        map(|x| x.split_once('-').expect("dash in there"))
+        .map(|x| (x.0.parse::<u64>().expect("Parse error on 0"), x.1.parse::<u64>().expect("Parse error on 1")))
+        .collect::<Vec<_>>();
+
+    return Problem{
+        ranges,
+    };
+}
+
+fn compute_problem(problem: &mut Problem) -> u64 {
+    //Potentialy ensure it is not overlapping
+    let problem = clean_problem(problem);
+    let count = problem.ranges.par_iter().map(|range| compute_range(range.0, range.1)).sum::<u64>();
+
+    return count;
+}
+
+fn clean_problem(problem: &Problem) -> CleanedProblem {
+    let new_ranges = problem.ranges.iter().map(|(lower, upper)|{
+        if (upper < lower){
+            return vec![]
+        }
+
+        let digitCountU = count_digits(*upper);
+        let digitCountL = count_digits(*lower);
+
+        if (digitCountL == digitCountU){
+            return vec![(*lower, *upper, digitCountU)];
+        }
+
+        let lowestOfDegree = lowest_of_degree(digitCountU);
+
+        return vec![(*lower, lowestOfDegree-1, digitCountL), (lowestOfDegree, *upper, digitCountU)];
+    }).flatten().collect::<Vec<_>>();
+
+  return CleanedProblem{ranges: new_ranges};
+}
+
+fn lowest_of_degree(degree : NonZeroU32) -> u64{
+    10u64.pow(degree.get() - 1)
+}
+
+fn compute_range(lower_bound: u64, upper_bound: u64) -> u64 {
+
+    let digitCount = count_digits(lower_bound);
+
+    (lower_bound..=upper_bound).map(|i|{
+        if is_combination(i) {
+            Some(i)
+        }else{
+            None
+        }
+    }).flatten().sum()
+}
+
+fn count_digits(mut n : u64) -> NonZeroU32{
+    let mut count = 0u64;
+
+    while (n != 0){
+        n = n / 10;
+        count +=1 ;
+    }
+
+    return unsafe{NonZeroU32::new_unchecked(count as u32)};
+}
+
+fn is_combination(n: u64) -> bool {
+    let digit_count = count_digits(n).get();
+
+    (1..=digit_count)
+        .filter(|count| digit_count % count == 0)
+        .filter(|count| *count <= digit_count/ 2)
+        .any(|count| {
+            let mask = 10u64.pow(count as u32);
+            let block = n % mask;
+
+            let mut x = n;
+            while x > 0 {
+                if x % mask != block {
+                    return false;
+                }
+                x /= mask;
+            }
+            true
+        })
+}
+
diff --git a/rust-workspace/.gitignore b/rust-workspace/.gitignore
new file mode 100644
index 0000000..185ca35
--- /dev/null
+++ b/rust-workspace/.gitignore
@@ -0,0 +1,3 @@
+/target
+
+.idea
diff --git a/rust-workspace/Cargo.lock b/rust-workspace/Cargo.lock
new file mode 100644
index 0000000..59ae180
--- /dev/null
+++ b/rust-workspace/Cargo.lock
@@ -0,0 +1,61 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9dd111b7b7f7d55b72c0a6ae361660ee5853c9af73f70c3c2ef6858b950e2e51"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
+
+[[package]]
+name = "either"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
+
+[[package]]
+name = "rayon"
+version = "1.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "368f01d005bf8fd9b1206fb6fa653e6c4a81ceb1466406b81792d87c5677a58f"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22e18b0f0062d30d4230b2e85ff77fdfe4326feb054b9783a3460d8435c8ab91"
+dependencies = [
+ "crossbeam-deque",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "rust-workspace"
+version = "0.1.0"
+dependencies = [
+ "rayon",
+]
diff --git a/rust-workspace/Cargo.toml b/rust-workspace/Cargo.toml
new file mode 100644
index 0000000..20fa284
--- /dev/null
+++ b/rust-workspace/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "rust-workspace"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+rayon = "1.11.0"
diff --git a/rust-workspace/input.txt b/rust-workspace/input.txt
new file mode 100644
index 0000000..71d0e89
--- /dev/null
+++ b/rust-workspace/input.txt
@@ -0,0 +1 @@
+9595822750-9596086139,1957-2424,88663-137581,48152-65638,12354817-12385558,435647-489419,518494-609540,2459-3699,646671-688518,195-245,295420-352048,346-514,8686839668-8686892985,51798991-51835611,8766267-8977105,2-17,967351-995831,6184891-6331321,6161577722-6161678622,912862710-913019953,6550936-6625232,4767634976-4767662856,2122995-2257010,1194-1754,779-1160,22-38,4961-6948,39-53,102-120,169741-245433,92902394-92956787,531-721,64-101,15596-20965,774184-943987,8395-11781,30178-47948,94338815-94398813
\ No newline at end of file
diff --git a/rust-workspace/src/main.rs b/rust-workspace/src/main.rs
new file mode 100644
index 0000000..9d08ac8
--- /dev/null
+++ b/rust-workspace/src/main.rs
@@ -0,0 +1,114 @@
+use std::collections::HashSet;
+use std::io::Read;
+use std::iter;
+use std::num::{NonZero, NonZeroU32, NonZeroU64};
+use rayon::prelude::*;
+
+fn main() {
+    let mut problem = parse_problem();
+
+    println!("Count in total: {}", compute_problem(&mut problem))
+}
+
+#[derive(Debug)]
+struct Problem{
+    ranges: Vec<(u64, u64)>
+}
+
+#[derive(Debug)]
+struct CleanedProblem{
+    ranges: Vec<(u64, u64, NonZeroU32)>
+}
+
+fn parse_problem() -> Problem {
+    let mut input = String::new();
+    std::io::stdin().read_to_string(&mut input).expect("Failed to read input");
+
+    let ranges = input.split(',').
+        map(|x| x.split_once('-').expect("dash in there"))
+        .map(|x| (x.0.parse::<u64>().expect("Parse error on 0"), x.1.parse::<u64>().expect("Parse error on 1")))
+        .collect::<Vec<_>>();
+
+    return Problem{
+        ranges,
+    };
+}
+
+fn compute_problem(problem: &mut Problem) -> u64 {
+    //Potentialy ensure it is not overlapping
+    let problem = clean_problem(problem);
+    let count = problem.ranges.par_iter().map(|range| compute_range(range.0, range.1)).sum::<u64>();
+
+    return count;
+}
+
+fn clean_problem(problem: &Problem) -> CleanedProblem {
+    let new_ranges = problem.ranges.iter().map(|(lower, upper)|{
+        if (upper < lower){
+            return vec![]
+        }
+
+        let digitCountU = count_digits(*upper);
+        let digitCountL = count_digits(*lower);
+
+        if (digitCountL == digitCountU){
+            return vec![(*lower, *upper, digitCountU)];
+        }
+
+        let lowestOfDegree = lowest_of_degree(digitCountU);
+
+        return vec![(*lower, lowestOfDegree-1, digitCountL), (lowestOfDegree, *upper, digitCountU)];
+    }).flatten().collect::<Vec<_>>();
+
+  return CleanedProblem{ranges: new_ranges};
+}
+
+fn lowest_of_degree(degree : NonZeroU32) -> u64{
+    10u64.pow(degree.get() - 1)
+}
+
+fn compute_range(lower_bound: u64, upper_bound: u64) -> u64 {
+
+    let digitCount = count_digits(lower_bound);
+
+    (lower_bound..=upper_bound).map(|i|{
+        if is_combination(i) {
+            Some(i)
+        }else{
+            None
+        }
+    }).flatten().sum()
+}
+
+fn count_digits(mut n : u64) -> NonZeroU32{
+    let mut count = 0u64;
+
+    while (n != 0){
+        n = n / 10;
+        count +=1 ;
+    }
+
+    return unsafe{NonZeroU32::new_unchecked(count as u32)};
+}
+
+fn is_combination(n: u64) -> bool {
+    let digit_count = count_digits(n).get();
+
+    (1..=digit_count)
+        .filter(|count| digit_count % count == 0)
+        .filter(|count| *count <= digit_count/ 2)
+        .any(|count| {
+            let mask = 10u64.pow(count as u32);
+            let block = n % mask;
+
+            let mut x = n;
+            while x > 0 {
+                if x % mask != block {
+                    return false;
+                }
+                x /= mask;
+            }
+            true
+        })
+}
+
diff --git a/rust-workspace/test_input.txt b/rust-workspace/test_input.txt
new file mode 100644
index 0000000..bd04584
--- /dev/null
+++ b/rust-workspace/test_input.txt
@@ -0,0 +1 @@
+11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124
\ No newline at end of file