finish 93

src/euler93/src/main.rs

@@ -1,69 +1,115 @@
+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 digits = Digits(1., 2., 3., 4.);
+    let mut digits_length = vec![];
 
-    let mut all_possible_integers = digits.all_possible_integers();
+    for quadruple_vec in ALL_DIGITS.into_iter().permutations(4) {
+        let quadruple = vec_to_quadruple(quadruple_vec);
 
-    all_possible_integers.sort();
+        let digits = Digits(quadruple);
 
-    let mut result = 0;
+        let permutations = digits.permutations();
 
-    for (i, num) in all_possible_integers.into_iter().enumerate() {
-        if i + 1 == num as usize {
-            result += 1;
+        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 {
-            break;
-        }
-    }
-}
-
-fn recurse(array: &[Num]) -> Vec<Num> {
-    if array.len() == 2 {
-        let [a, b] = array else { panic!() };
-
-        let mut v = vec![];
-
-        for ops in Operations::iter() {
-            v.push(ops(*a, *b));
-        }
-        v
-    } else {
-        let a = array[0];
-        let b = array[1];
-
-        let mut v = vec![];
-
-        for ops in Operations::iter() {
-            v.push(ops(a, b));
-        }
-    }
-}
-
-struct Digits(Num, Num, Num, Num);
-
-impl Digits {
-    fn all_possible_integers(&self) -> Vec<u32> {
-        let array = [self.0, self.1, self.2, self.3];
-
-        array.into_iter().permutations(4).next().map(|a| {
-            for ops in Operations::iter() {
-                let x = ops(a[0], a[1]);
+                Ordering::Greater
             }
         });
 
-        // dbg!(v);
+        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();
 
-        todo!()
+        let length = number_consecutive_positive_integers(result);
 
-        // let outcomes: Vec<_> = Operations::new()
-        //     .map(|f| f(a, b) as u32)
-        //     .filter(|i| *i > 0)
-        //     .collect();
+        digits_length.push((quadruple, length));
+    }
 
-        // dbg!(outcomes)
+    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]
     }
 }
 
@@ -72,7 +118,7 @@ struct Operations {
 }
 
 impl Iterator for Operations {
-    type Item = Box<dyn FnOnce(Num, Num) -> Num>;
+    type Item = Box<dyn Fn(Num, Num) -> Num>;
 
     fn next(&mut self) -> Option<Self::Item> {
         self.last += 1;