TheAlmostLuckyNumbersDivTwo | 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:: TheAlmostLuckyNumbersDivTwo
Method:: find
Parameters:: int, int
Returns:: int
Method signature:: int find(int a, int b)
(be sure your method is public)

Constraints

a will be between 1 and 1,000,000, inclusive.
b will be between a and 1,000,000, 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.
```
1234
```
```
4321
```
```
Returns: 36
```

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