C++ Program to Find Factorial of a Number using Dynamic Programming

The factorial of a positive integer n is equal to 1*2*3*...n. Factorial of a negative number does not exist. Here a C++ program is given to find out the factorial of a given input using dynamic programming.

Algorithm

Begin
   fact(int n):
      Read the number n
      Initialize
      i = 1, result[1000] = {0}
      result[0] = 1
      for i = 1 to n
         result[i] = I * result[i-1]
   Print result
End

Example Code

#include <iostream>
using namespace std;
int result[1000] = {0};
int fact(int n) {
   if (n >= 0) {
      result[0] = 1;
      for (int i = 1; i <= n; ++i) {
         result[i] = i * result[i - 1];
      }
      return result[n];
   }
}
int main() {
   int n;
   while (1) {
      cout<<"Enter integer to compute factorial (enter 0 to exit): ";
      cin>>n;
      if (n == 0)
      break;
      cout<<fact(n)<<endl;
   }
   return 0;
}

Output

Enter integer to compute factorial (enter 0 to exit): 2
2
Enter integer to compute factorial (enter 0 to exit): 6
720
Enter integer to compute factorial (enter 0 to exit): 7
5040
Enter integer to compute factorial (enter 0 to exit): 10
3628800
Enter integer to compute factorial (enter 0 to exit): 0