fix combinations for 51 (WIP)

euler51/src/combination.rs

@@ -0,0 +1,77 @@
+struct PositionCombinations {
+    min_length: usize,
+    state: Vec<bool>,
+    finished: bool,
+}
+
+impl Iterator for PositionCombinations {
+    type Item = Vec<bool>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.finished {
+            return None;
+        }
+        loop {
+            let result = self.state.clone();
+            self.increment();
+            if result.iter().filter(|x| **x).count() >= self.min_length {
+                return Some(result);
+            }
+        }
+    }
+}
+
+impl PositionCombinations {
+    fn new(min_length: usize, max_length: usize) -> Self {
+        let state = vec![false; max_length];
+        let finished = false;
+        Self {
+            min_length,
+            state,
+            finished,
+        }
+    }
+
+    fn increment(&mut self) {
+        let mut overflow = self.state[0];
+        self.state[0] ^= true;
+        for position in self.state[1..].iter_mut() {
+            let new_overflow = *position & overflow;
+            *position ^= overflow;
+            overflow = new_overflow;
+        }
+        if overflow {
+            self.finished = true;
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test_combination() {
+        use crate::combination::PositionCombinations;
+        use std::collections::HashSet;
+
+        let combinator = PositionCombinations::new(2, 4);
+        let result: HashSet<_> = combinator.into_iter().collect();
+        let mut number_solutions = result.len();
+        let mut solution = HashSet::new();
+        solution.insert(vec![false, false, true, true]);
+        solution.insert(vec![false, true, false, true]);
+        solution.insert(vec![false, true, true, false]);
+        solution.insert(vec![false, true, true, true]);
+        solution.insert(vec![true, true, false, false]);
+        solution.insert(vec![true, false, true, false]);
+        solution.insert(vec![true, false, false, true]);
+        solution.insert(vec![true, false, true, true]);
+        solution.insert(vec![true, true, false, true]);
+        solution.insert(vec![true, true, true, false]);
+        solution.insert(vec![true, true, true, true]);
+        for item in solution {
+            assert!(result.contains(&item));
+            number_solutions -= 1;
+        }
+        assert_eq!(number_solutions, 0);
+    }
+}

euler51/src/main.rs

@@ -1,4 +1,4 @@
-mod permutation;
+mod combination;
 mod primes;
 
 use crate::primes::Primes;
@@ -13,8 +13,8 @@ const DIGITS: [Int; 10] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
 // const MAX_VALUE: Int = 10_010_000;
 // const MAX_VALUE: Int = 99_999_999;
 
-const LENGTH_OF_NUMBERS: usize = 5;
-const MIN_LENGTH: usize = 2;
+// const LENGTH_OF_NUMBERS: usize = 5;
+// const MIN_LENGTH: usize = 2;
 
 fn main() {
     let primes = Primes::get_between(MIN_VALUE, MAX_VALUE);
@@ -63,7 +63,7 @@ fn digits_to_num(vec: Vec<Int>) -> Int {
 
 #[cfg(test)]
 mod test {
-    use crate::{digits_to_num, num_to_digits, primes::Primes, Int, MAX_VALUE, MIN_VALUE};
+    use crate::{digits_to_num, num_to_digits};
 
     #[test]
     fn test_digits_to_num() {

euler51/src/permutation.rs

@@ -1,75 +0,0 @@
-struct PositionPermut {
-    max_length: usize,
-    number_of_digits: usize,
-    idx: usize,
-    total_number_of_iterations: usize,
-}
-
-impl Iterator for PositionPermut {
-    type Item = Vec<i64>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        if self.idx == (self.total_number_of_iterations) {
-            return None;
-        };
-        let pos1 = self.idx % self.number_of_digits;
-        let pos0 = 0;
-        let x = vec![pos0 as i64, pos1 as i64];
-        let result = Some(x);
-        self.idx += 1;
-        result
-    }
-}
-
-impl PositionPermut {
-    fn new(max_length: usize) -> Self {
-        assert!(max_length >= 3);
-        let total_number_of_iterations = (1..max_length + 1).sum();
-        Self {
-            max_length,
-            number_of_digits: 2,
-            idx: 0,
-            total_number_of_iterations,
-        }
-    }
-    fn test(&mut self) {
-        // length_of_numbers = 4
-        // number_of_digits = 2
-        [0, 1];
-        [0, 2];
-        [0, 3];
-        [1, 2];
-        [1, 3];
-        [2, 3];
-        // number_of_digits = 3
-        [0, 1, 2];
-        [0, 1, 3];
-        [0, 2, 3];
-        [1, 2, 3];
-    }
-}
-
-#[cfg(test)]
-mod test {
-    #[test]
-    fn test_permutation() {
-        use crate::permutation::PositionPermut;
-        use std::collections::HashSet;
-
-        let permutator = PositionPermut::new(3);
-        let result: HashSet<_> = permutator.into_iter().collect();
-        let mut solution = HashSet::new();
-        solution.insert(vec![0, 1]);
-        solution.insert(vec![0, 2]);
-        solution.insert(vec![0, 3]);
-        solution.insert(vec![1, 2]);
-        solution.insert(vec![1, 3]);
-        solution.insert(vec![2, 3]);
-        // solution.insert(vec![0, 1, 2]);
-        // solution.insert(vec![0, 1, 3]);
-        // solution.insert(vec![0, 2, 3]);
-        // solution.insert(vec![1, 2, 3]);
-        // assert_eq!(result.len(), solution.len());
-        assert_eq!(result, solution);
-    }
-}