Olimpiade Sains Nasional (OSN) 2006 - Komputer, Nomor 4

Untuk menciptakan 0 di digit akhir di perlukan bilangan 10. Faktor dari 10 itu 2 dan 5, jadi kita cukup mencari 5 saja.

C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int N;
    cin >> N;
    int zeroCount = 0, divider = 5;
    while(N >= divider)
    {
        zeroCount += (N/divider);
        divider *= 5;
    }
    cout << zeroCount << "\n";
    return 0;
}

Java (ZeroCountInFactorial.java)

import java.util.Scanner;
public class ZeroCountInFactorial {

     public static void main(String []args){
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int zeroCount = 0, divider = 5;
        while(N >= divider)
        {
            zeroCount += (N/divider);
            divider *= 5;
        }
        System.out.println(zeroCount);
     }
}

var i, count : integer;
	N : longint;
	A : array[1..10000] of longint;

BEGIN
readln(N);
count := 0;
i := 2;
A[1] := 5;
repeat
 A[i] := A[i-1] * 5;
 count := count + (N div A[i-1]);
 inc(i);
until (N < A[i-1]);
writeln(count);
END.