TheAlmostLuckyNumbersDivOne | Topcoder Archive

Problem Statement

John and Brus believe that the digits 4 and 7 are lucky and all others are not. According to them, an almost lucky number is a number that contains at most one non-lucky digit in its decimal representation. Return the total number of almost lucky numbers between a and b, inclusive.

Definition

Class:: TheAlmostLuckyNumbersDivOne
Method:: find
Parameters:: long, long
Returns:: long
Method signature:: long find(long a, long b)
(be sure your method is public)

Constraints

a will be between 1 and 10^16, inclusive.
b will be between a and 10^16, inclusive.

Examples

```
4
```
```
7
```
```
Returns: 4
```
All numbers between 4 and 7 are almost lucky.
```
8
```
```
19
```
```
Returns: 4
```
Numbers 8, 9, 14 and 17 are almost lucky.
```
28
```
```
33
```
```
Returns: 0
```
No almost lucky numbers here.
```
12345678900
```
```
98765432100
```
```
Returns: 91136
```

This problem statement is the exclusive and proprietary property of Topcoder, Inc. Any unauthorized use or reproduction of this information without the prior written consent of Topcoder, Inc. is strictly prohibited. (c)2024, Topcoder, Inc. All rights reserved.