Recursion/Iteration - Factorial
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using System;
class MainClass
{
static void Main()
{
// Factorial - is going down from the number multiplying each till reach 1
// e.g. of 5 or 5! = 5 * 4 * 3 * 2 * 1 = 120
// Functions that find the factorial of any number
Console.WriteLine($"Iterative: {FindFactorialIterative(5)}");
Console.WriteLine($"Recursive: {FindFactorialRecursive(5)}");
}
static int FindFactorialRecursive(int number) //O(n)
{
if (number == 0 || number == 1) { return 1; }
if (number == 2) { return 2; }
return number * FindFactorialRecursive(number - 1);
}
static int FindFactorialIterative(int number) //O(n)
{
int answer = 1;
if (number == 0 || number == 1) { return 1; } // 0x1
if (number == 2) { return 2; } // 1x2
for (int i = 2; i <= number; i++) { answer *= i; }
return answer;
}
}
// Iterative
// answer is 1, then 2, then 6, then 24
// i is 2, then 3 then 4 then 5
// (1xi2) (2xi3) (6xi4) (24xi5)
// Recursive
// The function called inside of the function is seperate with ITS OWN parameter each time
Csharp
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