Add Project Euler problem 94 solution 1 (#8599)

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DIRECTORY.md

@@ -937,6 +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

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() = }")