Find all factorial numbers less than or equal to n

A number N is called a factorial number if it is the factorial of a positive integer. For example, the first few factorial numbers are

1, 2, 6, 24, 120, …

Given a number n, print all factorial numbers smaller than or equal to n.

Examples :

Input : n = 100
Output : 1 2 6 24

Input : n = 1500
Output : 1 2 6 24 120 720

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

A simple solution is to generate all factorials one by one until the generated factorial is greater than n.

An efficient solution is to find next factorial using previous factorial.

C++

 // CPP program to find all factorial numbers // smaller than or equal to n. #include using namespace std;    void printFactorialNums(int n) {     int fact = 1;     int x = 2;     while (fact <= n) {         cout << fact << " ";            // Compute next factorial          // using previous         fact = fact * x;            x++;     } }    // Driver code int main() {     int n = 100;     printFactorialNums(n);     return 0; }

Java

 // Java program to find all factorial numbers // smaller than or equal to n.    class GFG {     static void printFactorialNums(int n)     {         int fact = 1;         int x = 2;         while (fact <= n)         {             System.out.print(fact + " ");                    // Compute next factorial              // using previous             fact = fact * x;                    x++;         }     }            // Driver code     public static void main (String[] args)      {         int n = 100;         printFactorialNums(n);     } }    // This code is contributed by Anant Agarwal.

Python3

 # Python3 program to find all factorial  # numbers smaller than or equal to n.    def printFactorialNums( n):     fact = 1     x = 2     while fact <= n:         print(fact, end = " ")                    # Compute next factorial         # using previous         fact = fact * x                    x += 1    # Driver code n = 100 printFactorialNums(n)    # This code is contributed by "Abhishek Sharma 44"

C#

 // C# program to find all factorial numbers // smaller than or equal to n. using System;    class GFG {     static void printFactorialNums(int n)     {         int fact = 1;         int x = 2;         while (fact <= n)         {             Console.Write(fact + " ");                    // Compute next factorial              // using previous             fact = fact * x;                    x++;         }     }            // Driver code     public static void Main ()      {         int n = 100;         printFactorialNums(n);     } }    // This code is contributed by vt_m.

PHP



Output:

1 2 6 24

Time Complexity : O(n)

If there are multiple queries, then we can cache all previously computed factorial numbers to avoid re-computations.

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Improved By : vt_m, jit_t

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