1 Day 1 Algorithms

[2019.03.15] Extra Long Factorials

곰돌찌 2019. 3. 15. 09:11

Problem


The factorial of the integer , written , is defined as:

Calculate and print the factorial of a given integer.

For example, if , we calculate  and get .

Function Description

Complete the extraLongFactorials function in the editor below. It should print the result and return.

extraLongFactorials has the following parameter(s):

  • n: an integer

Note: Factorials of  can't be stored even in a  long long variable. Big integers must be used for such calculations. Languages like Java, Python, Ruby etc. can handle big integers, but we need to write additional code in C/C++ to handle huge values.

We recommend solving this challenge using BigIntegers.

Input Format

Input consists of a single integer 

Constraints

Output Format

Print the factorial of .

Sample Input

Sample Output

Explanation

The factorial of the integer , written , is defined as:

Calculate and print the factorial of a given integer.르

For example, if , we calculate  and get .

Function Description

Complete the extraLongFactorials function in the editor below. It should print the result and return.

extraLongFactorials has the following parameter(s):

  • n: an integer

Note: Factorials of  can't be stored even in a  long long variable. Big integers must be used for such calculations. Languages like Java, Python, Ruby etc. can handle big integers, but we need to write additional code in C/C++ to handle huge values.

We recommend solving this challenge using BigIntegers.

Input Format

Input consists of a single integer 

Constraints

Output Format

Print the factorial of .

Sample Input

Sample Output

Explanation

25! = 25 x 24 x 23 x ....... x 3 x 2 x 1


How I solved the problem


# BigInteger Class 를 활용함.

# BigInteger는 숫자 크기에 제한이 없음. 즉, 무한대의 정수를 넣을 수 있음.


# BigInteger를 사용하여 사칙연산을 할 때는 +, -, *, / 등을 사용할 수 없음.

# 즉, 매서드를 활용해야함. 

# 더하기는 add(), 빼기는 substract(), 곱하기는 multiply(), 나누기는 divide()를 사용함...

# 그리고 BigInteger.ONE을 하면 1을 의미하고.. 정수의 값들을 BigInteger class에 담기 위해서는 BigInteger.valueOf()를 사용해줘야함!


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import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;
 
public class Solution {
 
    // Complete the extraLongFactorials function below.
    static void extraLongFactorials(int n) {
        BigInteger result = BigInteger.ONE;
 
        for (int i = 0; i < n; i++) {
            result = result.multiply(BigInteger.valueOf(i + 1));
        }
 
        System.out.println(result);
    }
 
    private static final Scanner scanner = new Scanner(System.in);
 
    public static void main(String[] args) {
        int n = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
 
        extraLongFactorials(n);
 
        scanner.close();
    }
}
 
cs

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