Create factorial.py

2024_05_31_DataStructures/factorial.py

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+# Use the command below to perform doctest
+# python3 -m doctest factorial.py -v
+
+def factorial_iteration(n):
+    """
+    >>> factorial_iteration(3)
+    6
+    >>> factorial_iteration(0)
+    1
+    >>> factorial_iteration(1)
+    1
+    """
+    if type(n) is str:
+        raise TypeError("Cannot have string factorial")
+
+    if type(n) not in [int]:
+        raise TypeError("Cannot have non-integer factorial")
+
+    if n < 0:
+        raise ValueError("Cannot have negative factorial")
+
+    result = 1;
+    for i in range(n, 1, -1):
+        result = i*result
+
+    return result
+
+def factorial_dynamic_programming(n):
+    if type(n) is str:
+        raise TypeError("Cannot have string factorial")
+
+    if type(n) not in [int]:
+        raise TypeError("Cannot have non-integer factorial")
+
+    if n < 0:
+        raise ValueError("Cannot have negative factorial")
+
+    factorial_list = [-1] * (n+1)
+    factorial_list[0] = 1
+
+    for i in range(1, n+1, 1):
+        factorial_list[i] = factorial_list[i-1] * i
+
+    return factorial_list[n]
+
+def main():
+    user_number = int( input("Enter a number to get its factorial result: ") )
+    # x = factorial_iteration(user_number)
+    x = factorial_dynamic_programming(user_number)
+    print("The result of ", user_number, "! is ", x)
+
+if __name__ == "__main__":
+    main()