diff --git a/lib/dijkstra/src/lib.rs b/lib/dijkstra/src/lib.rs
index bc1eed1..8e87a8b 100644
--- a/lib/dijkstra/src/lib.rs
+++ b/lib/dijkstra/src/lib.rs
@@ -96,18 +96,18 @@ where
         while !(self.unvisited_without_distance.is_empty()
             && self.unvisited_with_distance.is_empty())
         {
-            let coord = self.get_unvisited_coord_with_smallest_distance_from_start();
-            let neighbours = self.get_neighbours(&coord);
-            let previous_distance = *self.matrix.get(coord).unwrap().get_distance().unwrap();
+            let to_visit = self.get_unvisited_coord_with_smallest_distance_from_start();
+            self.visit(to_visit);
+            let neighbours = self.get_neighbours(&to_visit);
+            let previous_distance = *self.matrix.get(to_visit).unwrap().get_distance().unwrap();
             for neighbour in neighbours {
-                self.update_neighbour(neighbour, coord, previous_distance);
+                self.update_neighbour(neighbour, to_visit, previous_distance);
             }
         }
     }
 
     fn get_unvisited_coord_with_smallest_distance_from_start(&mut self) -> Coordinate {
-        let coord = self
-            .unvisited_with_distance
+        self.unvisited_with_distance
             .iter()
             .filter_map(|c| {
                 let node = self.matrix.get(*c).unwrap();
@@ -115,9 +115,11 @@ where
             })
             .reduce(|(c0, v0), (c1, v1)| if v0 < v1 { (c0, v0) } else { (c1, v1) })
             .map(|(c, _)| *c)
-            .unwrap_or(self.start);
+            .unwrap_or(self.start)
+    }
+
+    fn visit(&mut self, coord: (usize, usize)) {
         self.unvisited_with_distance.remove(&coord);
-        coord
     }
 
     fn get_neighbours(&self, coordinate: &Coordinate) -> Vec<Coordinate> {
diff --git a/lib/primes/src/lib.rs b/lib/primes/src/lib.rs
index dd5f505..040a978 100644
--- a/lib/primes/src/lib.rs
+++ b/lib/primes/src/lib.rs
@@ -6,12 +6,13 @@ use std::fs::File;
 use std::hash::Hash;
 use std::io::Write;
 use std::slice::Iter;
+use std::vec::IntoIter;
 
 use num::FromPrimitive;
 use num::Num;
 use num::ToPrimitive;
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct Primes<T> {
     vector: Vec<T>,
     set: HashSet<T>,
@@ -110,6 +111,10 @@ where
     pub fn into_vec(self) -> Vec<T> {
         self.vector
     }
+
+    pub fn to_cloned_iter(&self) -> IntoIter<T> {
+        self.vector.clone().into_iter()
+    }
 }
 
 #[cfg(test)]
diff --git a/src/euler200/src/main.rs b/src/euler200/src/main.rs
index 2797ffa..40f328b 100644
--- a/src/euler200/src/main.rs
+++ b/src/euler200/src/main.rs
@@ -13,39 +13,45 @@ fn main() {
     squbes.iterate();
     squbes.iterate();
     squbes.iterate();
-    println!("{:?}", squbes.output());
+    println!("{:?}", squbes.get_output());
 }
 
 #[derive(Debug)]
 struct Squbes {
     squbes: HashSet<u64>,
-    new_squbes: Vec<u64>,
-    primes: IntoIter<u64>,
+    primes: Primes<u64>,
+    primes_iter: IntoIter<u64>,
     used_primes: Vec<u64>,
     current_prime: u64,
 }
 
 impl Squbes {
     pub fn new(max: u64) -> Self {
-        let mut primes = Primes::get_between(2, max).into_vec().into_iter();
-        let first = primes.next().unwrap();
-        let second = primes.next().unwrap();
+        let primes = Primes::get_between(2, max);
+        let mut primes_iter = primes.to_cloned_iter();
+        let first = primes_iter.next().unwrap();
+        let second = primes_iter.next().unwrap();
         Self {
             squbes: HashSet::new(),
-            new_squbes: vec![],
             primes,
+            primes_iter,
             used_primes: vec![first],
             current_prime: second,
         }
     }
 
     pub fn iterate(&mut self) {
-        self.calculate_squbes_with_current_prime();
+        let squbes = self.calculate_squbes_with_current_prime();
         self.save_current_prime();
         self.update_current_prime();
+        self.save_new_squbes();
     }
 
-    pub fn output(&self) -> Vec<u64> {
+    fn save_new_squbes(&mut self) {
+        todo!()
+    }
+
+    pub fn get_output(&self) -> Vec<u64> {
         let mut result: Vec<_> = self.squbes.iter().copied().collect();
         result.sort_unstable();
         result
@@ -56,27 +62,27 @@ impl Squbes {
     }
 
     fn update_current_prime(&mut self) {
-        self.current_prime = self.primes.next().unwrap();
+        self.current_prime = self.primes_iter.next().unwrap();
     }
 
-    fn calculate_squbes_with_current_prime(&mut self) {
-        assert_ne!(self.current_prime, 0);
-        let iter = self
-            .used_primes
-            .iter()
-            .copied()
-            .zip([self.current_prime].into_iter().cycle())
-            .chain(
-                [self.current_prime]
-                    .into_iter()
-                    .cycle()
-                    .zip(self.used_primes.iter().copied()),
-            )
-            .map(|(p, q)| Self::core(p, q));
-        self.new_squbes.extend(iter);
+    fn calculate_squbes_with_current_prime(&mut self) -> Vec<u64> {
+        get_iterator_over_pairs_both_ways(&self.used_primes, self.current_prime)
+            .map(|(p, q)| Self::core(p, q))
+            .collect()
     }
 
     fn core(p: u64, q: u64) -> u64 {
         p.pow(2) * q.pow(3)
     }
 }
+
+fn get_iterator_over_pairs_both_ways(
+    vec: &[u64],
+    value: u64,
+) -> impl Iterator<Item = (u64, u64)> + '_ {
+    iterate_vec_and_scalar(vec, value).flat_map(|(x, y)| [(x, y), (y, x)].into_iter())
+}
+
+fn iterate_vec_and_scalar(vec: &[u64], value: u64) -> impl Iterator<Item = (u64, u64)> + '_ {
+    vec.iter().copied().zip([value].into_iter().cycle())
+}
diff --git a/src/euler85/Cargo.toml b/src/euler85/Cargo.toml
new file mode 100644
index 0000000..d5b1234
--- /dev/null
+++ b/src/euler85/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "euler85"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/src/euler85/src/main.rs b/src/euler85/src/main.rs
new file mode 100644
index 0000000..b26c2ab
--- /dev/null
+++ b/src/euler85/src/main.rs
@@ -0,0 +1,66 @@
+const TARGET: usize = 2_000_000;
+
+fn main() {
+    let mut x = 1_000;
+    let mut y = 2;
+
+    let mut grid = Grid::new(x, y);
+    let mut number;
+    let mut best_grid = grid.clone();
+    let mut best_diff = 5_000_000;
+    loop {
+        number = grid.number_rectangles();
+        let diff = number.abs_diff(TARGET);
+        if diff < best_diff {
+            best_diff = diff;
+            best_grid = grid.clone();
+        }
+        if number < TARGET {
+            y += 1;
+        } else {
+            x -= 1;
+        }
+        if x == 1 {
+            break;
+        }
+
+        grid = Grid::new(x, y);
+    }
+
+    let area = best_grid.area();
+    println!("{area}");
+}
+
+#[derive(Debug, Clone)]
+struct Grid {
+    x: usize,
+    y: usize,
+}
+
+impl Grid {
+    fn new(x: usize, y: usize) -> Self {
+        Self { x, y }
+    }
+
+    fn number_rectangles(&self) -> usize {
+        let mut result = 0;
+
+        for x in 1..=self.x {
+            for y in 1..=self.y {
+                result += self.fits(x, y);
+            }
+        }
+
+        result
+    }
+
+    fn fits(&self, x: usize, y: usize) -> usize {
+        let fits_in_x = self.x - (x - 1);
+        let fits_in_y = self.y - (y - 1);
+        fits_in_x * fits_in_y
+    }
+
+    fn area(&self) -> usize {
+        self.x * self.y
+    }
+}
diff --git a/src/euler86/Cargo.toml b/src/euler86/Cargo.toml
new file mode 100644
index 0000000..4e96566
--- /dev/null
+++ b/src/euler86/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "euler86"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[profile.release]
+lto = "fat"
+debug = true
+
diff --git a/src/euler86/src/main.rs b/src/euler86/src/main.rs
new file mode 100644
index 0000000..9334990
--- /dev/null
+++ b/src/euler86/src/main.rs
@@ -0,0 +1,60 @@
+use std::f64::EPSILON;
+
+const TARGET: u32 = 1_000_000;
+
+fn main() {
+    let mut m = 1;
+    let mut distinct = 0;
+
+    loop {
+        println!("trying: {m}");
+
+        for x in 1..m + 1 {
+            for y in x..m + 1 {
+                let z = m;
+                let c = Cuboid::new(x, y, z);
+                if c.shortest_path_is_integer() {
+                    distinct += 1;
+                };
+            }
+        }
+
+        if distinct > TARGET {
+            break;
+        }
+
+        m += 1;
+    }
+
+    println!("\n{m}");
+}
+
+struct Cuboid {
+    x: u32,
+    y: u32,
+    z: u32,
+}
+
+impl Cuboid {
+    fn new(x: u32, y: u32, z: u32) -> Self {
+        Self { x, y, z }
+    }
+
+    fn shortest_path_is_integer(&self) -> bool {
+        // because of the way we iterator over x, y and z, these are guaranteed to be in order
+        // and therefore produces the shortest path
+        let shortest_path = pythagorean(self.x + self.y, self.z);
+
+        is_integer(shortest_path)
+    }
+}
+
+fn pythagorean(x: u32, y: u32) -> f64 {
+    ((x.pow(2) + y.pow(2)) as f64).sqrt()
+}
+
+fn is_integer(result: f64) -> bool {
+    let rounded = result.round();
+
+    (result - rounded).abs() <= EPSILON
+}
diff --git a/src/euler92/Cargo.toml b/src/euler92/Cargo.toml
new file mode 100644
index 0000000..93ea1b7
--- /dev/null
+++ b/src/euler92/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "euler92"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[profile.release]
+lto = "fat"
diff --git a/src/euler92/src/main.rs b/src/euler92/src/main.rs
new file mode 100644
index 0000000..24c4785
--- /dev/null
+++ b/src/euler92/src/main.rs
@@ -0,0 +1,38 @@
+const MAXIMUM: usize = 10_000_000;
+
+fn main() {
+    let mut arrives_at_89 = 0;
+
+    for i in 1..MAXIMUM {
+        let mut number = i;
+        loop {
+            let sum: usize = number
+                .to_digits()
+                .into_iter()
+                .map(|d| d.pow(2) as usize)
+                .sum();
+            if sum == 89 {
+                arrives_at_89 += 1;
+                break;
+            } else if sum == 1 {
+                break;
+            }
+            number = sum;
+        }
+    }
+
+    println!("{arrives_at_89}");
+}
+
+trait ToDigits {
+    fn to_digits(&self) -> Vec<u8>;
+}
+
+impl ToDigits for usize {
+    fn to_digits(&self) -> Vec<u8> {
+        self.to_string()
+            .chars()
+            .map(|c| c.to_digit(10).unwrap() as _)
+            .collect()
+    }
+}
diff --git a/src/euler93/Cargo.toml b/src/euler93/Cargo.toml
new file mode 100644
index 0000000..69a13a5
--- /dev/null
+++ b/src/euler93/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "euler93"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+itertools = "*"
diff --git a/src/euler93/src/main.rs b/src/euler93/src/main.rs
new file mode 100644
index 0000000..e84eb7a
--- /dev/null
+++ b/src/euler93/src/main.rs
@@ -0,0 +1,141 @@
+use std::cmp::Ordering;
+
+use itertools::Itertools;
+
+type Num = f64;
+type Quadruple = [Num; 4];
+
+const ALL_DIGITS: [Num; 10] = [0., 1., 2., 3., 4., 5., 6., 7., 8., 9.];
+
+fn main() {
+    let mut digits_length = vec![];
+
+    for quadruple_vec in ALL_DIGITS.into_iter().permutations(4) {
+        let quadruple = vec_to_quadruple(quadruple_vec);
+
+        let digits = Digits(quadruple);
+
+        let permutations = digits.permutations();
+
+        let mut results: Vec<_> = permutations
+            .into_iter()
+            .flat_map(find_integer_results)
+            .collect();
+
+        results.sort_unstable_by(|n1, n2| {
+            if n1 < n2 {
+                Ordering::Less
+            } else {
+                Ordering::Greater
+            }
+        });
+
+        let result = results
+            .into_iter()
+            .tuple_windows()
+            .filter(|(v0, v1)| (v1 - v0) > Num::EPSILON)
+            .map(|(n1, _)| n1) // TODO last number may be missing?
+            .collect_vec();
+
+        let length = number_consecutive_positive_integers(result);
+
+        digits_length.push((quadruple, length));
+    }
+
+    digits_length.sort_unstable_by(|a, b| a.1.cmp(&b.1));
+
+    let mut result = digits_length.last().unwrap().0;
+
+    result.sort_by(Num::total_cmp);
+
+    let s: String = result
+        .into_iter()
+        .map(|d| char::from_digit(d as u32, 10).unwrap())
+        .collect();
+
+    println!("{s}");
+}
+
+fn number_consecutive_positive_integers(result: Vec<f64>) -> usize {
+    let length = result.len();
+
+    result
+        .into_iter()
+        .tuple_windows()
+        .filter(|(a, b)| b - 1.5 > *a)
+        .map(|(a, _)| a.round() as usize)
+        .next()
+        .unwrap_or(length)
+}
+
+fn find_integer_results(quadruple: Quadruple) -> Vec<Num> {
+    let [i0, i1, i2, i3] = quadruple;
+
+    let mut result = vec![];
+
+    for op1 in Operations::iter() {
+        for op2 in Operations::iter() {
+            for op3 in Operations::iter() {
+                let num = op3(op2(op1(i0, i1), i2), i3);
+                if num > 0. && is_integer(num) {
+                    result.push(num);
+                }
+            }
+        }
+    }
+
+    result
+}
+
+fn is_integer(num: Num) -> bool {
+    (num.round() - num).abs() <= Num::EPSILON
+}
+
+struct Digits(Quadruple);
+
+impl Digits {
+    fn permutations(&self) -> Vec<Quadruple> {
+        self.0
+            .into_iter()
+            .permutations(4)
+            .map(vec_to_quadruple)
+            .collect()
+    }
+}
+
+fn vec_to_quadruple(v: Vec<f64>) -> Quadruple {
+    unsafe {
+        let i0 = *v.get_unchecked(0);
+        let i1 = *v.get_unchecked(1);
+        let i2 = *v.get_unchecked(2);
+        let i3 = *v.get_unchecked(3);
+        [i0, i1, i2, i3]
+    }
+}
+
+struct Operations {
+    last: usize,
+}
+
+impl Iterator for Operations {
+    type Item = Box<dyn Fn(Num, Num) -> Num>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.last += 1;
+        match self.last {
+            1 => Some(Box::new(|l, r| l + r)),
+            2 => Some(Box::new(|l, r| l - r)),
+            3 => Some(Box::new(|l, r| r - l)),
+            4 => Some(Box::new(|l, r| l * r)),
+            5 => Some(Box::new(|l, r| l / r)),
+            6 => Some(Box::new(|l, r| r / l)),
+            _ => None,
+        }
+    }
+}
+
+impl Operations {
+    fn iter() -> Self {
+        Self { last: 0 }
+    }
+}
diff --git a/src/euler94/Cargo.toml b/src/euler94/Cargo.toml
new file mode 100644
index 0000000..0f099c5
--- /dev/null
+++ b/src/euler94/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "euler94"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+f128 = "0.2.9"
+num-traits = "0.2.15"
+
+[profile.release]
+lto = "fat"
+codegen-units = 1
diff --git a/src/euler94/src/main.rs b/src/euler94/src/main.rs
new file mode 100644
index 0000000..f6a0fa2
--- /dev/null
+++ b/src/euler94/src/main.rs
@@ -0,0 +1,55 @@
+type Num = usize;
+
+fn main() {
+    let mut sum = 0;
+
+    let mut i = 5;
+    'outer: loop {
+        if i > 333_333_334 {
+            break;
+        }
+        let a = i;
+
+        if a % 2 == 0 {
+            i += 1;
+            continue;
+        }
+
+        for c in [a - 1, a + 1] {
+            let t = Triangle::new(a, c);
+
+            if t.has_integer_area() {
+                println!("{:.10}, {:.10}", t.a, t.c);
+                sum += t.perimeter();
+                i = ((i as f64) * 3.59).trunc() as usize;
+                continue 'outer;
+            }
+        }
+
+        i += 1;
+    }
+
+    println!("{sum:.15}");
+}
+
+struct Triangle {
+    a: Num,
+    c: Num,
+}
+
+impl Triangle {
+    fn new(a: Num, c: Num) -> Self {
+        Self { a, c }
+    }
+
+    fn perimeter(&self) -> Num {
+        2 * self.a + self.c
+    }
+
+    fn has_integer_area(&self) -> bool {
+        let h = 4 * self.a.pow(2) - self.c.pow(2);
+        let root = (h as f64).sqrt().trunc() as usize;
+
+        root * root == h
+    }
+}
diff --git a/src/euler95/Cargo.toml b/src/euler95/Cargo.toml
new file mode 100644
index 0000000..269262f
--- /dev/null
+++ b/src/euler95/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "euler95"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dev-dependencies]
+rstest = "0.17"
+
+[profile.release]
+debug = true
+lto = "fat"
diff --git a/src/euler95/src/main.rs b/src/euler95/src/main.rs
new file mode 100644
index 0000000..6decb83
--- /dev/null
+++ b/src/euler95/src/main.rs
@@ -0,0 +1,118 @@
+use std::collections::HashSet;
+
+const MAX: usize = 1_000_000;
+
+fn main() {
+    let mut chains = vec![];
+
+    let mut part_of_any_chain = HashSet::new();
+
+    for current in 1..MAX {
+        if part_of_any_chain.contains(&current) {
+            continue;
+        }
+        try_build_chain_from_number(MAX, current, &mut chains, &mut part_of_any_chain);
+    }
+
+    chains.sort_by_key(|chain| chain.len());
+
+    let longest = chains.last().unwrap();
+
+    let smallest = longest.iter().min().unwrap().to_owned();
+
+    println!("{smallest}");
+}
+
+fn build_proper_divisors(max: usize) -> Vec<Vec<usize>> {
+    todo!()
+}
+
+fn try_build_chain_from_number(
+    max: usize,
+    mut current: usize,
+    chains: &mut Vec<Vec<usize>>,
+    part_of_any_chain: &mut HashSet<usize>,
+) {
+    let mut maybe_chain = vec![];
+
+    loop {
+        maybe_chain.push(current);
+
+        let next: usize = get_proper_divisors(current).into_iter().sum();
+
+        if next > max || next == 0 {
+            break;
+        }
+
+        if maybe_chain.contains(&next) {
+            if maybe_chain.len() > 1 && *maybe_chain.first().unwrap() == next {
+                for number in &maybe_chain {
+                    part_of_any_chain.insert(*number);
+                }
+                println!("{}", maybe_chain.first().unwrap());
+                chains.push(maybe_chain);
+            }
+            break;
+        }
+
+        current = next;
+    }
+}
+
+fn get_proper_divisors(x: usize) -> Vec<usize> {
+    let mut result = vec![1];
+
+    let limit = x / 2 + 1;
+
+    for i in 2..limit {
+        if result.contains(&i) {
+            break;
+        }
+
+        if x % i == 0 {
+            let div_1 = i;
+            let div_2 = x / i;
+            result.push(div_1);
+
+            if div_2 != div_1 {
+                result.push(div_2);
+            }
+        }
+    }
+
+    result.sort_unstable();
+    result
+}
+
+#[cfg(test)]
+mod tests {
+
+    use rstest::rstest;
+
+    #[rstest]
+    #[case(6, vec![1, 2, 3])]
+    #[case(28, vec![1, 2, 4, 7, 14])]
+    #[case(12_496, vec![1, 2, 4, 8, 11, 16, 22, 44, 71, 88, 142, 176, 284, 568, 781, 1136, 1562, 3124, 6248])]
+    fn proper_divisor(#[case] input: usize, #[case] expected: Vec<usize>) {
+        use crate::get_proper_divisors;
+
+        assert_eq!(get_proper_divisors(input), expected);
+    }
+
+    #[rstest]
+    #[case(220, vec![vec![220, 284]])]
+    #[case(12_496, vec![vec![12_496, 14_288, 15_472, 14_536, 14_264]])]
+    fn chain(#[case] input: usize, #[case] expected: Vec<Vec<usize>>) {
+        use std::collections::HashSet;
+
+        use crate::try_build_chain_from_number;
+
+        let max = expected.iter().flatten().max().unwrap().to_owned();
+        let mut part_of_any_chain = HashSet::new();
+
+        let mut chains = vec![];
+        try_build_chain_from_number(max, input, &mut chains, &mut part_of_any_chain);
+
+        assert_eq!(chains, expected);
+    }
+}