Project Euler 41

#include <iostream>
#include <algorithm>
using namespace std;
const int n= 7654322;
bool esPrimo[n+1];
void generarCriba()
{
    for(int i = 3 ; i <= n; i+=2)
        esPrimo[i] = true;
    for(int i = 4 ; i <= n; i+=2)
        esPrimo[i] = false;
    esPrimo[2] = true;
    for(int i = 3; i*i <= n; i+=2)
        if(esPrimo[i])
            for(int j = i+i ; j <= n; j+=i)
                esPrimo[j] = false;
}
int main()
{
    generarCriba();
    string ini = "7654321";
    string fin = "1234567";
    int i = 0 ;
    while(ini.compare(fin)!=0)
    {
        if(((ini[6]-'0')&1)!=0)
            if(esPrimo[atoi(ini.data())])
            {
                cout << ini << endl;
                break;
            }
        prev_permutation(ini.begin(),ini.end());
    }
    return 0;
}

Project Euler 37

#include <iostream>
#include <bitset>
#include <math.h>
using namespace std;
bool esPrimo(int n)
{
    if(n==1)
        return false;
    for(int i = 2; i*i<=n; i++)
        if(n%i==0)
            return false;
    return true;
}

bool esCPI(int n)
{
    int nc = 10;
    while(nc<n)
    {
        if(!esPrimo(n%nc))
            return false;
        nc *= 10;
    }
    return true;
}
int main()
{

    int ini=0,fin=0;
    int term[] = {1,3,7,9};
    int td[100]= {2,3,5,7};

    int pos=4;
    ini = 0;
    fin = 3;
    for(int cd = 1; cd<=9; cd++)
    {
        for(int i=ini ; i<=fin; i++)
        {
            for(int t = 0 ; t<=3; t++)
            {
                int ope = td[i]*10+term[t];
                if(esPrimo(ope))
                    td[pos++] = ope;
            }
        }
        ini = fin+1;
        fin = pos-1;
    }
    int sum = 0 ,cant = 0;
    for(int i = 4; i<=fin ; i++)
        if(esCPI(td[i]))
        {
            cout << td[i] << endl;
            sum += td[i];
            cant++;
        }
    cout << "cantidad total = "<<cant<<endl;
    cout << "resultado final = "<<sum<<endl;
    return 0;
}

Project Euler 36

#include <iostream>
#include <string>
using namespace std;
bool esPalindrome(string cad)
{
    int i,j;
    i = 0;
    j = cad.size()-1;
    while(i<j)
        if(cad[i++]!=cad[j--])
            return false;
    return true;
}
string abase2(int n)
{
    string sol = "";
    while(n>0)
        sol = (char)((n&1)+'0')+sol , n >>= 1;
    return sol;
}
string aString(int n)
{
    string sol = "";
    while(n>0)
    {
        int d = n%10;
        sol = (char)(d+'0')+sol;
        n /= 10;
    }
 
    return sol;
}
int main()
{
//872187
    int suma = 0 ;
    const int n = 1000000;
    for(int i = 1; i < n; i+=2)
        if(esPalindrome(aString(i)) && esPalindrome(abase2(i)))
            suma += i;
    cout << suma << endl;
    return 0;
}

Project Euler 35

#include <iostream>
#include <bitset>
using namespace std;
const int n = 1000000;
bitset<n+1> criba;
void generarCriba()
{
    criba[0] = criba[1] = true;
    for(int i = 2 ; i*i<=n; i++)
        if(!criba[i])
            for(int j = i+i; j<=n; j +=i )
                criba[j]= true;

}
int main()
{
    generarCriba();
    int cont = 4;//2,3,5,7 ya cuentan como primos circulares
    int cc = 1;
    int sncc= 100;
    int nc = 10;
    for(int i = 10 ; i<n; i++)
    {
        if(i==sncc)
        {
            cc++;
            sncc *=10;
            nc *= 10;
        }
        if(!criba[i])
        {
            int num = i;
            int c = 0;

            for(int u = 1 ; u<=cc; u++)
            {
                int d = num%10;
                num /= 10;
                num = (d*nc+num);
                if(!criba[num])
                    c++;
                else
                    break;
            }

            if(c == cc)
                cont++;
        }
    }
    cout <<"Resultado final = "<< cont<< endl;
    return 0;
}

Project Euler 34

#include <iostream>

using namespace std;

int main()
{
    int sum = 0 ;
    int fac[10] = {1,1,2};
    for(int i = 3; i<=9; i++)
        fac[i] = i*fac[i-1];
    int num = 0;
    int n[5]= {0};
    for(n[0] = 0 ; n[0]<10 ; n[0]++)
        for(n[1] = 0 ; n[1]<10 ; n[1]++)
            for(n[2] = 0 ; n[2]<10 ; n[2]++)
                for(n[3] = 0 ; n[3]<10 ; n[3]++)
                    for(n[4]= 0 ; n[4]<10 ; n[4]++)
                    {
                        int pos = 0 ;
                        while(pos <=4 && n[pos]==0)
                            pos++;
                        if(fac[n[0]]+fac[n[1]]+fac[n[2]]+fac[n[3]]+fac[n[4]]-pos==num)
                        {
                            cout << n[0] << "! + ";
                            cout << n[1] << "! + ";
                            cout << n[2] << "! + ";
                            cout << n[3] << "! + ";
                            cout << n[4] << "! = " << num<< endl;

                            sum += num;
                        }
                        num++;
                    }
    cout << sum-3<< endl;
    /*Le restamos 3 por que en el enunciado
      indica que no hay que sumar 1! = 1 y 2! = 2
        */
    return 0;
}

Project Euler 33

#include <iostream>

using namespace std;

int mcd(int a,int b)
{
    int c;
    if(b>a)
    {
        c = a;
        a = b;
        b = c;
    }
    c = a%b;
    while(c > 0)
    {
        a = b;
        b = c;
        c = a%b;
    }
    return b;
}

int main()
{
    int mcdiv;
    int de,nu;
    int resultadoden  = 1;
    int resultadonum = 1;
    for(int num = 10; num<=50; num++)
        for(int den = 10; den <= 99 ; den++)
        {
            mcdiv = mcd(num,den);
            if(num != den && mcdiv!=1 && mcdiv%10!=0)
            {
                de = den/mcdiv;
                nu = num/mcdiv;
                int dat1[2]= {num/10,num%10};
                int dat2[2]= {den/10,den%10};
                for(int i=0; i<=1; i++)
                    for(int j = 0; j<=1; j++)
                        if(dat1[i]!=0 && dat2[j]!=0 &&
                                dat1[i]%nu==0 &&
                                dat2[j]%de==0 &&
                                (dat1[i]/nu)==(dat2[j]/de) &&
                                (dat1[(i+1)%2]==dat2[(j+1)%2]))
                        {
                            cout << num<<"/"<<den<<" = "<<dat1[i]<<"/"<<dat2[j]<<endl;
                            resultadoden *= den;
                            resultadonum *= num;
                        }
            }
        }
    cout << "Resultado final = "<< resultadoden/mcd(resultadonum,resultadoden) <<endl;

    return 0;
}

Project Euler 32

#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <set>
#include <numeric>
using namespace std;
int factorial(int n)
{
    int f  = 1;
    while(n>0)
        f *= n--;
    return f;
}
int main()
{
    set<int> guardar ;
    string cad =  "123456789";
    int tam =  cad.length();
    int n1,n2,n3,i,j;
    int fac = factorial(tam);

    for(int n = 0 ; n < fac; n++)
    {
        for(i = 1 ; i <=(tam-2) ; i++ )
        {
            n1 = atoi(cad.substr(0,i).data());
            for(j = 1 ; j <= (tam-i-1); j++)
            {
                n2 = atoi(cad.substr(i,j).data());
                n3 = atoi(cad.substr(i+j,tam-i+j).data());
                if((n1*n2) == n3)
                {
                    cout << n1 << " x "<<n2 <<" = "<<n3<<endl;
                    guardar.insert(n3);
                }
            }
        }
        next_permutation(cad.begin(),cad.end());
    }
    cout << "Resultado Final = "<<accumulate(guardar.begin(),guardar.end(),0)<<endl;
    return 0;
}