PE 088 WIP, hard problem

projecteuler/088/src/main.rs

@@ -1,15 +1,39 @@
-use std::time::Instant;
+use num_traits::{identities::One, Num};
+use std::{
+    cmp::min,
+    collections::{hash_map::RandomState, HashSet},
+    time::Instant,
+};
 
-fn product(v: &Vec<u32>) -> u32 {
-    v.iter().fold(1, |acc, &v_x| acc * v_x)
+fn product<T: Num + Copy>(v: &Vec<T>) -> T {
+    v.iter().fold(One::one(), |acc, &v_x| acc * v_x)
 }
 
 fn naive_solution(k: u32) -> u32 {
-    todo!()
+    let max_ps = 2 * k;
+    let mut numbers = vec![1; k as usize];
+    let mut result = u32::MAX;
+    let mut idx = k as usize - 1;
+
+    while numbers[0] <= k {
+        let p = product(&numbers);
+        let s = numbers.iter().sum::<u32>();
+
+        if p == s {
+            result = min(result, p);
+            return result;
+        } else if p > max_ps || s > max_ps {
+            idx -= 1;
+        } else {
+            numbers[idx] += 1;
+        }
+    }
+
+    return 0;
 }
 
 // ChatGPT failing once again
-fn chatgpt_solution(k: u32) -> u32 {
+fn _chatgpt_solution(k: u32) -> u32 {
     let mut prod = vec![2 * k; k as usize + 1];
     let mut sums = vec![2 * k; k as usize + 1];
 
@@ -40,9 +64,11 @@ fn main() {
     let now = Instant::now();
 
     let max_k = 12;
-
     let solution = naive_solution;
-    let result: u32 = (2..=max_k).into_iter().map(|k| solution(k)).sum();
+
+    let results: Vec<u32> = ((2..=max_k).into_iter().map(|k| solution(k))).collect();
+    let hash_results: HashSet<u32, RandomState> = HashSet::from_iter(results.into_iter());
+    let result: u32 = hash_results.into_iter().sum();
 
     println!(
         "The sum of all minimal product-sum numbers for 2 <= k <= {} is: {}",