Update readme, create factorial_examples folder and move existing code into it

factorial_examples/README.md

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+Some example factorial functions in various programming languages

factorial_examples/factorial.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdint.h>
+
+uintmax_t factorial(uintmax_t n) {
+	if(n < 2)
+		return 1;
+	return n * factorial(n-1);
+}
+
+uintmax_t factorial_iter(uintmax_t n) {
+	uintmax_t fact = 1;
+	uintmax_t i = 2;
+	while(i <= n) {
+		fact *= i;
+		i++;
+	}
+	return fact;
+}
+
+int main(void) {
+	size_t bufsize = 1024;
+	char **lineptr = calloc(bufsize, sizeof(char));
+	fputs("Enter number to factor: ", stdout);
+	int err = getline(lineptr, &bufsize, stdin);
+	if(err == -1) {
+		puts("Error reading line from user input");
+		return 1;
+	}
+
+	uintmax_t user_input = abs(atoi(*lineptr));
+	printf("\nRecursive factorial for number: %ju\n", factorial(user_input));
+	printf("Iterative factorial for number: %ju\n", factorial_iter(user_input));
+	free(lineptr);
+	return 0;
+}

factorial_examples/factorial.py

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+def factorial(n: int) -> int:
+    if n < 2:
+        return n
+    else:
+        return n * factorial(n-1)
+
+def factorial_iter(n: int) -> int:
+    fact = 1
+    # Grab absolute value to ensure n is a positive integer
+    n = abs(n)
+    for i in range(2, n+1):
+        fact *= i
+    return fact
+
+user_input = int(input("Insert number to calculate factorial for: "))
+
+# Avoid recursion limit
+if user_input < 1000:
+    print(f"Recursive factorial {user_input}: {factorial(user_input)}")
+print(f"Iterative factorial {user_input}: {factorial_iter(user_input)}")