feat(challenge-153/lubos-kolouch/python/ch-1.py): Challenge 153 Task 1 Python LK

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+""" Challenge 153 Task 1"""
+
+
+class LeftFactCalculator:
+    """Challenge 153 Task 1"""
+
+    def __init__(self):
+        # keep seen factorials in a cache to speed things up
+        self.fact_cache = {0: 1}
+        self.left_fact_cache = {0: 0}
+
+    def calculate_factorial(self, what: int):
+        """Calculate factorial on one number"""
+
+        try:
+            return self.fact_cache[what]
+        except KeyError:
+            pass
+
+        # let's utilize the fact that we are processing the numbers in sequence
+        self.fact_cache[what] = what * self.fact_cache[what - 1]
+
+        return self.fact_cache[what]
+
+    def calculate_left_fact(self, what: int):
+        """Calculate the left factorial of one number"""
+
+        try:
+            return self.left_fact_cache[what]
+        except KeyError:
+            pass
+
+        # let's utilize the fact that we are processing the numbers in sequence
+        self.left_fact_cache[what] = (
+            self.calculate_factorial(what - 1) + self.left_fact_cache[what - 1]
+        )
+
+        return self.left_fact_cache[what]
+
+    def get_left_factorial(self, what: int):
+        """Get the solution for the task"""
+
+        output = []
+
+        for i in range(1, what + 1):
+            output.append(self.calculate_left_fact(i))
+
+        return output
+
+
+def main():
+    calculator = LeftFactCalculator()
+    assert calculator.get_left_factorial(10) == [
+        1,
+        2,
+        4,
+        10,
+        34,
+        154,
+        874,
+        5914,
+        46234,
+        409114,
+    ]
+
+
+if __name__ == "__main__":
+    main()