Remove extra len calls in doubly-linked-list's methods (#8600)

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

DIRECTORY.md

@@ -317,6 +317,7 @@
   * [Longest Sub Array](dynamic_programming/longest_sub_array.py)
   * [Matrix Chain Order](dynamic_programming/matrix_chain_order.py)
   * [Max Non Adjacent Sum](dynamic_programming/max_non_adjacent_sum.py)
+  * [Max Product Subarray](dynamic_programming/max_product_subarray.py)
   * [Max Sub Array](dynamic_programming/max_sub_array.py)
   * [Max Sum Contiguous Subsequence](dynamic_programming/max_sum_contiguous_subsequence.py)
   * [Min Distance Up Bottom](dynamic_programming/min_distance_up_bottom.py)
@@ -936,6 +937,8 @@
     * [Sol1](project_euler/problem_091/sol1.py)
   * Problem 092
     * [Sol1](project_euler/problem_092/sol1.py)
+  * Problem 094
+    * [Sol1](project_euler/problem_094/sol1.py)
   * Problem 097
     * [Sol1](project_euler/problem_097/sol1.py)
   * Problem 099
@@ -1016,6 +1019,8 @@
     * [Sol1](project_euler/problem_587/sol1.py)
   * Problem 686
     * [Sol1](project_euler/problem_686/sol1.py)
+  * Problem 800
+    * [Sol1](project_euler/problem_800/sol1.py)
 
 ## Quantum
   * [Bb84](quantum/bb84.py)

data_structures/linked_list/doubly_linked_list.py

@@ -81,7 +81,9 @@ class DoublyLinkedList:
             ....
         IndexError: list index out of range
         """
-        if not 0 <= index <= len(self):
+        length = len(self)
+
+        if not 0 <= index <= length:
             raise IndexError("list index out of range")
         new_node = Node(data)
         if self.head is None:
@@ -90,7 +92,7 @@ class DoublyLinkedList:
             self.head.previous = new_node
             new_node.next = self.head
             self.head = new_node
-        elif index == len(self):
+        elif index == length:
             self.tail.next = new_node
             new_node.previous = self.tail
             self.tail = new_node
@@ -131,15 +133,17 @@ class DoublyLinkedList:
             ....
         IndexError: list index out of range
         """
-        if not 0 <= index <= len(self) - 1:
+        length = len(self)
+
+        if not 0 <= index <= length - 1:
             raise IndexError("list index out of range")
         delete_node = self.head  # default first node
-        if len(self) == 1:
+        if length == 1:
             self.head = self.tail = None
         elif index == 0:
             self.head = self.head.next
             self.head.previous = None
-        elif index == len(self) - 1:
+        elif index == length - 1:
             delete_node = self.tail
             self.tail = self.tail.previous
             self.tail.next = None

project_euler/problem_094/sol1.py

@@ -0,0 +1,44 @@
+"""
+Project Euler Problem 94: https://projecteuler.net/problem=94
+
+It is easily proved that no equilateral triangle exists with integral length sides and
+integral area. However, the almost equilateral triangle 5-5-6 has an area of 12 square
+units.
+
+We shall define an almost equilateral triangle to be a triangle for which two sides are
+equal and the third differs by no more than one unit.
+
+Find the sum of the perimeters of all almost equilateral triangles with integral side
+lengths and area and whose perimeters do not exceed one billion (1,000,000,000).
+"""
+
+
+def solution(max_perimeter: int = 10**9) -> int:
+    """
+    Returns the sum of the perimeters of all almost equilateral triangles with integral
+    side lengths and area and whose perimeters do not exceed max_perimeter
+
+    >>> solution(20)
+    16
+    """
+
+    prev_value = 1
+    value = 2
+
+    perimeters_sum = 0
+    i = 0
+    perimeter = 0
+    while perimeter <= max_perimeter:
+        perimeters_sum += perimeter
+
+        prev_value += 2 * value
+        value += prev_value
+
+        perimeter = 2 * value + 2 if i % 2 == 0 else 2 * value - 2
+        i += 1
+
+    return perimeters_sum
+
+
+if __name__ == "__main__":
+    print(f"{solution() = }")

project_euler/problem_800/sol1.py

@@ -0,0 +1,65 @@
+"""
+Project Euler Problem 800: https://projecteuler.net/problem=800
+
+An integer of the form p^q q^p with prime numbers p != q is called a hybrid-integer.
+For example, 800 = 2^5 5^2 is a hybrid-integer.
+
+We define C(n) to be the number of hybrid-integers less than or equal to n.
+You are given C(800) = 2 and C(800^800) = 10790
+
+Find C(800800^800800)
+"""
+
+from math import isqrt, log2
+
+
+def calculate_prime_numbers(max_number: int) -> list[int]:
+    """
+    Returns prime numbers below max_number
+
+    >>> calculate_prime_numbers(10)
+    [2, 3, 5, 7]
+    """
+
+    is_prime = [True] * max_number
+    for i in range(2, isqrt(max_number - 1) + 1):
+        if is_prime[i]:
+            for j in range(i**2, max_number, i):
+                is_prime[j] = False
+
+    return [i for i in range(2, max_number) if is_prime[i]]
+
+
+def solution(base: int = 800800, degree: int = 800800) -> int:
+    """
+    Returns the number of hybrid-integers less than or equal to base^degree
+
+    >>> solution(800, 1)
+    2
+
+    >>> solution(800, 800)
+    10790
+    """
+
+    upper_bound = degree * log2(base)
+    max_prime = int(upper_bound)
+    prime_numbers = calculate_prime_numbers(max_prime)
+
+    hybrid_integers_count = 0
+    left = 0
+    right = len(prime_numbers) - 1
+    while left < right:
+        while (
+            prime_numbers[right] * log2(prime_numbers[left])
+            + prime_numbers[left] * log2(prime_numbers[right])
+            > upper_bound
+        ):
+            right -= 1
+        hybrid_integers_count += right - left
+        left += 1
+
+    return hybrid_integers_count
+
+
+if __name__ == "__main__":
+    print(f"{solution() = }")

scripts/project_euler_answers.json

@@ -723,5 +723,112 @@
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 }