UVA 11827 - Maximum GCD

/***
	Md. Nazmul Hasan
	Shahjalal University of Science & Technology,Sylhet.
	hasan08sust@gmail.com
	***/
	#include<iostream>
	#include<cstdio>
	#include<stack>
	#include<queue>
	#include<map>
	#include<vector>
	#include<algorithm>
	#include<cstring>
	#include<sstream>
	#include<cmath>
	#include <iomanip>
	using namespace std ;
	typedef long long ll ;
	typedef int in ;
	typedef unsigned long long ull ;
	const double pi = 2*acos(0) ;
	#define maxi 40000
	#define pf printf
	#define sc scanf
	#define pb push_back
	#define MEM(x,y) (memset((x),(y),sizeof(x)))
	#define MIN(x,y) ((x) < (y) ? (x) : (y))
	#define MAX(x,y) ((x) > (y) ? (x) : (y))
	#define load(array,size) for(int i=0 ; i<size ; i++) cin>>array[i] ;
	#define new_line pf("\n")
	#define clear_data(array) memset(array,0,sizeof(array))
	#define highest_int 2147483647
	int GCD(int a, int b)
	{
	if(a%b==0) return b;
	return GCD(b,a%b);
	}
	int main()
	{
	int test,p,mx,a,b,val;
	string str;
	vector<int>data;
	sc("%d",&test);
	getchar();
	while(test--)
	{
	getline(cin,str);
	stringstream ss(str);
	while(ss>>p)
	{
	data.pb(p);
	}
	mx =0 ;
	for(int i=0 ; i<data.size()-1 ; i++)
	{
	for(int j=i+1 ; j<data.size() ; j++)
	{
	a = data[i];
	b = data[j];
	val = GCD(a,b);
	//pf("GCD OF %d & %d is %d\n",a,b,val);
	if(mx<val)
	{
	mx = val;
	}
	}
	}
	pf("%d\n",mx);
	data.clear();
	}
	return 0;
	}

UVA 412 Pi

/***
	Md. Nazmul Hasan
	Shahjalal University of Science & Technology,Sylhet.
	hasan08sust@gmail.com
	***/
	#include<iostream>
	#include<cstdio>
	#include<stack>
	#include<queue>
	#include<map>
	#include<vector>
	#include<algorithm>
	#include<cstring>
	#include<sstream>
	#include<cmath>
	#include <iomanip>
	using namespace std ;
	typedef long long ll ;
	typedef int in ;
	typedef unsigned long long ull ;
	const double pi = 2*acos(0) ;
	#define maxi 40000
	#define pf printf
	#define sc scanf
	#define pb push_back
	#define MEM(x,y) (memset((x),(y),sizeof(x)))
	#define MIN(x,y) ((x) < (y) ? (x) : (y))
	#define MAX(x,y) ((x) > (y) ? (x) : (y))
	#define load(array,size) for(int i=0 ; i<size ; i++) cin>>array[i] ;
	#define new_line pf("\n")
	#define clear_data(array) memset(array,0,sizeof(array))
	#define highest_int 2147483647
	int GCD(int a, int b)
	{
	if(a%b==0) return b;
	return GCD(b,a%b);
	}
	int main()
	{
	int n,m,p,cnt,a,b,d;
	vector<int>data;
	while(sc("%d",&n))
	{
	if(n<=1 || n>=50)
	break;
	m = n-1;
	cnt =0 ;
	int total = m*(m+1)/2;
	for(int i=0 ; i<n ; i++)
	{
	sc("%d",&p);
	data.pb(p);
	}
	for(int i=0 ; i<data.size()-1 ; i++)
	{
	//j = i+1;
	for(int j = i+1 ; j<data.size() ; j++)
	{
	a = data[i];
	b = data[j];
	d = GCD(a,b);
	if(d==1)
	{
	cnt++;
	//pf("-> %d %d\n",a,b);
	}
	}
	}
	if(cnt==0)
	{
	pf("No estimate for this data set.\n");
	}
	else
	{
	double val = (6*total*1.0)/cnt ;
	double pi = sqrt(val);
	pf("%.6lf\n",pi);
	}
	data.clear();
	}
	return 0;
	}

UVA 10490 Mr. Azad and his Son!!!!!

/***
Md. Nazmul Hasan
Shahjalal University of Science & Technology,Sylhet.
hasan08sust@gmail.com
***/
#include<iostream>
#include<cstdio>
#include<stack>
#include<queue>
#include<map>
#include<vector>
#include<algorithm>
#include<cstring>
#include<sstream>
#include<cmath>
#include <iomanip>
using namespace std ;
typedef long long ll ;
typedef int in ;
typedef unsigned long long ull ;
const double pi = 2*acos(0) ;
#define maxi 40000
#define pf printf
#define sc scanf
#define pb push_back
#define MEM(x,y) (memset((x),(y),sizeof(x)))
#define MIN(x,y) ((x) < (y) ? (x) : (y))
#define MAX(x,y) ((x) > (y) ? (x) : (y))
#define load(array,size)  for(int i=0 ; i<size ; i++) cin>>array[i]  ;
#define new_line  pf("\n")
#define clear_data(array) memset(array,0,sizeof(array))
#define highest_int 2147483647


int main()
{
    int n,cnt;
    long long int m;
    int prime[] = {2,3,5,7,11,13,17,19,23,29,31};

    while(sc("%d",&n) &&n)
    {
        cnt=0;

        for(int i=0 ; i<11 ; i++)
        {
            if(n==prime[i])
                cnt=1;
        }


        if(cnt==1)
        {
            if(n==11 || n==23 || n==29)
            {
                pf("Given number is prime. But, NO perfect number is available.\n");
            }
            else
            {
                m = pow(2,n-1)*(pow(2,n)-1);
                pf("Perfect: %lld!\n",m);
            }
        }
        else
        {
            pf("Given number is NOT prime! NO perfect number is available.\n");
        }

    }

    return 0;
}