FarFromPrimes | Topcoder Archive

Problem Statement

A prime number is an integer greater than 1 that has no positive divisors other than 1 and itself. The first prime numbers are 2, 3, 5, 7, 11, 13, 17, ...

The number N is considered far from primes if there are no prime numbers between N-10 and N+10, inclusive, i.e., all numbers N-10, N-9, ..., N-1, N, N+1, ..., N+9, N+10 are not prime.

You are given an int A and an int B. Return the number of far from primes numbers between A and B, inclusive.

Definition

Class:: FarFromPrimes
Method:: count
Parameters:: int, int
Returns:: int
Method signature:: int count(int A, int B)
(be sure your method is public)

Constraints

A will be between 10 and 100000, inclusive.
B will be between A and 100000, inclusive.
(B - A) will be between 0 and 1000, inclusive.

Examples

```
3328
```
```
4100
```
```
Returns: 4
```
The far from primes numbers are 3480, 3750, 3978 and 4038.
```
10
```
```
1000
```
```
Returns: 0
```
```
19240
```
```
19710
```
```
Returns: 53
```
```
23659
```
```
24065
```
```
Returns: 20
```
```
97001
```
```
97691
```
```
Returns: 89
```

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