686 - Goldbach's Conjecture (II)

/***

            Bismillahir Rahmanir Rahim
            Read the name of Allah, who created you!!!
            Author : Shah Newaj Rabbi Shishir
            Department of CSE, City University, Bangladesh.

***/

#include <bits/stdc++.h>
using namespace std;

#define sf scanf
#define pf printf
#define scase sf ("%d",&tc)
#define sn sf ("%d",&n)
#define whilecase while (tc--)
#define eof while (cin >> n)
#define forloop for (pos=1; pos<=tc; pos++)
#define arrayloop (i=0; i<n; i++)
#define cinstr cin >> str
#define getstr getline (cin,str)
#define pcase pf ("Case %d: ",pos)
#define pb push_back

bool isPrime (int n)
{
    int i;
    bool k = true;

    if (n < 2 || (!(n & 1) && n != 2))
        return false;

    if (n == 2)
        return true;

    for (i=2; i*i<=n; i++)
    {
        if (n % i == 0)
        {
            k = false;
            break;
        }
    }

    return k;
}

int main (void)
{
    int num,h,i;

    while (cin >> num && num)
    {
        int count = 0, h = num/2;

        for (i=2; i<=h; i++)
            if (isPrime(i) && isPrime(num-i))
                count++;

        cout << count << endl;
    }

    return 0;
}

623 - 500!

/***

            Bismillahir Rahmanir Rahim
            Read the name of Allah, who created you!!!
            Author : Shah Newaj Rabbi Shishir
            Department of CSE, City University, Bangladesh.

***/

import java.util.Scanner;
import java.math.BigInteger;

public class Main
{
public static void main (String args[])
{
Scanner in = new Scanner (System.in);

int n,i;

while (in.hasNext())
{
n = in.nextInt ();

BigInteger fact = BigInteger.valueOf(1);

for (i=1; i<=n; i++)
fact = fact.multiply(BigInteger.valueOf(i));

System.out.println (n+"!\n"+fact);
}
}
}

583 - Prime Factors

/***

            Bismillahir Rahmanir Rahim
            Read the name of Allah, who created you!!!
            Author : Shah Newaj Rabbi Shishir
            Department of CSE, City University, Bangladesh.

***/

#include <bits/stdc++.h>
using namespace std;

#define sf scanf
#define pf printf
#define scase sf ("%d",&tc)
#define sn sf ("%d",&n)
#define whilecase while (tc--)
#define eof while (cin >> n)
#define forloop for (pos=1; pos<=tc; pos++)
#define arrayloop (i=0; i<n; i++)
#define cinstr cin >> str
#define getstr getline (cin,str)
#define pcase pf ("Case %d: ",pos)
#define pb push_back
#define in insert
#define llu unsigned long long
#define lld long long
#define U unsigned int

const long long MAX = 100005;
bool prime[MAX];
vector <long long> v;

void sieve ()
{
    long long i,j;

    prime[0] = prime[1] = true;
    v.pb(2);

    for (i=4; i<MAX; i+=2)
        prime[i] = true;

    for (i=3; i*i<MAX; i+=2)
        if (!prime[i])
            for (j=i*i; j<MAX; j+=2*i)
                prime[j] = true;

    for (i=3; i<MAX; i+=2)
        if (!prime[i])
            v.pb(i);
}

int main (void)
{
    /*freopen ("input.txt","r",stdin);
    freopen ("output.txt","w",stdout);*/
    sieve ();

    long long n,t,i,len;

    while (cin >> n && n)
    {
        vector <long long> f;
        t = n;

        if (n < 0)
        {
            n *= -1;
            f.pb(-1);
        }

        for (i=0; v[i]*v[i]<=n; i++)
        {
            while (n % v[i] == 0)
            {
                f.pb(v[i]);
                n /= v[i];
            }
        }

        if (n > 1)
            f.pb(n);

        len = f.size();

        pf ("%lld = ",t);

        for (i=0; i<len; i++)
        {
            pf ("%lld",f[i]);

            if (i == len-1)
                pf ("\n");
            else
                pf (" x ");
        }
    }

    return 0;
}

575 - Skew Binary

/***

            Bismillahir Rahmanir Rahim
            Read the name of Allah, who created you!!!
            Author : Shah Newaj Rabbi Shishir
            Department of CSE, City University, Bangladesh.

***/

#include <bits/stdc++.h>
using namespace std;

#define sf scanf
#define pf printf
#define scase sf ("%d",&tc)
#define sn sf ("%d",&n)
#define whilecase while (tc--)
#define eof while (cin >> n)
#define forloop for (pos=1; pos<=tc; pos++)
#define arrayloop (i=0; i<n; i++)
#define cinstr cin >> str
#define getstr getline (cin,str)
#define pcase pf ("Case %d: ",pos)
#define pb push_back
#define in insert
#define llu unsigned long long
#define lld long long
#define u unsigned int

int main (void)
{
    string str;
    int len,i,dec,k;

    while (cin >> str)
    {
        if (str == "0")
            break;

        k = len = str.size();
        dec = 0;

        for (i=0; i<len; i++)
            dec += (str[i]-'0') * (pow(2,k--) - 1);

        cout << dec << endl;
    }

    return 0;
}

568 - Just the Facts

/***

            Bismillahir Rahmanir Rahim
            Read the name of Allah, who created you!!!
            Author : Shah Newaj Rabbi Shishir
            Department of CSE, City University, Bangladesh.

***/

import java.util.Scanner;
import java.math.BigInteger;

public class Main
{
public static void main (String[] args)
{
Scanner in = new Scanner (System.in);

int n,temp,i,l;
String str;
char []Char = new char[1];

while (in.hasNext())
{
n = in.nextInt();

System.out.printf("%5d -> ",n);

BigInteger fact = BigInteger.valueOf(1);

for (i=1; i<=n; i++)
fact = fact.multiply(BigInteger.valueOf(i));

str = fact.toString();
Char = str.toCharArray();
l = Char.length-1;

int sum = 0;

for (i=l; i>=0; i--)
{
if (Char[i] != '0')
{
System.out.println(Char[i]);
break;
}
}
}
}
}