From a28244231a864ef22c1c18f7794d7756138d7319 Mon Sep 17 00:00:00 2001
From: Philippe Zwietering <philippe.zwietering@gmail.com>
Date: Sun, 16 Apr 2023 21:21:18 +0200
Subject: [PATCH] PE 088 WIP, hard problem

---
 projecteuler/088/Cargo.lock  | 18 ++++++++++++++++
 projecteuler/088/Cargo.toml  |  1 +
 projecteuler/088/src/main.rs | 40 +++++++++++++++++++++++++++++-------
 3 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/projecteuler/088/Cargo.lock b/projecteuler/088/Cargo.lock
index 88ffcd8..b91cfc3 100644
--- a/projecteuler/088/Cargo.lock
+++ b/projecteuler/088/Cargo.lock
@@ -2,6 +2,24 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
 [[package]]
 name = "main"
 version = "0.1.0"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "578ede34cf02f8924ab9447f50c28075b4d3e5b269972345e7e0372b38c6cdcd"
+dependencies = [
+ "autocfg",
+]
diff --git a/projecteuler/088/Cargo.toml b/projecteuler/088/Cargo.toml
index fca4e93..ec5f990 100644
--- a/projecteuler/088/Cargo.toml
+++ b/projecteuler/088/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+num-traits = "0.2.15"
diff --git a/projecteuler/088/src/main.rs b/projecteuler/088/src/main.rs
index 025be90..449598e 100644
--- a/projecteuler/088/src/main.rs
+++ b/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: {}",