Permutations with conditions

Question 1:

abc, is a three digit integer that provides the following conditions

condition 1 will cba > abc
condition 2 abc will prime number
condition 3 cba will prime number
condition 4 ab will prime number
condition 5 bc will prime number
condition 6 cb will prime number
condition 7 ba will prime number

Write a c# working code to satisfy all

Please help guys its urgent

Try this:

using System;

class Program

{

static void Main()

{

Console.WriteLine("The 3 digit integers which satisfy the conditions are:\n");

for(int i = 100; i < 1000; i++)

{

int[] d = GetDigits(i);

int cba = d[2] * 100 + d[1] * 10 + d[0];

if ((cba <= i) || !IsPrime(i) || !IsPrime(cba)) continue;

int ab = d[0] * 10 + d[1];

if(!IsPrime(ab)) continue;

int bc = d[1] * 10 + d[2];

if(!IsPrime(bc)) continue;

int cb = d[2] * 10 + d[1];

if(!IsPrime(cb)) continue;

int ba = d[1] * 10 + d[0];

if(!IsPrime(ba)) continue;

Console.WriteLine(i);

}

Console.ReadKey();

}

static bool IsPrime(int x)

{

if (x <= 1) return false;

for (int i = 2; i <= x / 2; i++)

{

if ((x % i) == 0)

{

return false;

}

return true;

}

static int[] GetDigits(int x)

{

int[] digits = new int[3];

digits[0] = x / 100;

x = x % 100;

digits[1] = x / 10;

digits[2] = x % 10;

return digits;

}

The output is :

The 3 digit integers which satisfy the conditions are:

113

179

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes12y ago
Accepted answer
Try this:

using System;

class Program
{
static void Main()
{
Console.WriteLine("The 3 digit integers which satisfy the conditions are:\n");

for(int i = 100; i < 1000; i++)
{
int[] d = GetDigits(i);
int cba = d[2] * 100 + d[1] * 10 + d[0];
if ((cba <= i) || !IsPrime(i) || !IsPrime(cba)) continue;
int ab = d[0] * 10 + d[1];
if(!IsPrime(ab)) continue;
int bc = d[1] * 10 + d[2];
if(!IsPrime(bc)) continue;
int cb = d[2] * 10 + d[1];
if(!IsPrime(cb)) continue;
int ba = d[1] * 10 + d[0];
if(!IsPrime(ba)) continue;
Console.WriteLine(i);
}

Console.ReadKey();
}

static bool IsPrime(int x)
{
if (x <= 1) return false;

for (int i = 2; i <= x / 2; i++)
{
if ((x % i) == 0)
{
return false;
}
}

return true;
}

static int[] GetDigits(int x)
{
int[] digits = new int[3];
digits[0] = x / 100;
x = x % 100;
digits[1] = x / 10;
digits[2] = x % 10;
return digits;
}
}

The output is :

The 3 digit integers which satisfy the conditions are:

113
179
Abiather Hore12y ago
thnx Vulpes it wrked