day 2

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
+        })
+}
+