Statistics

Problem Statement for "TheLuckyNumbersLevelOne"

Problem Statement

The digits 4 and 7 are lucky digits, and all other digits are unlucky. A first level lucky number is a positive integer whose decimal representation is a palindrome that contains only lucky digits. A palindrome is a number that reads the same forward and backward. John and Brus would like to count the number of first level lucky numbers within a specified range.

You are given longs a and b. Return the number of first level lucky numbers between a and b, inclusive.

Definition

Class:
TheLuckyNumbersLevelOne
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 10^18, inclusive.
  • b will be between a and 10^18, inclusive.

Examples

  1. 1

    100

    Returns: 4

    The first level lucky numbers within this range are 4, 7, 44 and 77.

  2. 45

    54

    Returns: 0

    There are no first level lucky numbers here.

  3. 477444774

    477444774

    Returns: 1

    The given range contains only one integer and it is a first level lucky number.

  4. 456789123

    789123456

    Returns: 24

  5. 70

    100

    Returns: 1

  6. 71

    76

    Returns: 0

  7. 15

    77

    Returns: 2

  8. 314415

    748518739

    Returns: 64

  9. 839685

    294794236

    Returns: 32

  10. 720206

    863378607

    Returns: 68

  11. 987391

    91823502

    Returns: 32

  12. 374770

    454911421

    Returns: 48

  13. 925976

    253992901

    Returns: 32

  14. 31515

    815601503

    Returns: 80

  15. 993966

    789622502

    Returns: 64

  16. 461339

    14618776

    Returns: 22

  17. 533801

    299889533

    Returns: 36

  18. 486946

    461720850

    Returns: 44

  19. 358787

    201840879

    Returns: 40

  20. 980234

    2395868

    Returns: 0

  21. 91972593928314415

    429437714725840869

    Returns: 0

  22. 554102594705839685

    871864155292650254

    Returns: 256

  23. 17438115591720206

    79807977131137660

    Returns: 512

  24. 725080559573987391

    948391076642202521

    Returns: 256

  25. 535282044706616000

    968493245237374770

    Returns: 256

  26. 220418497480925976

    385179090453708371

    Returns: 0

  27. 952794849364031515

    978499011279142477

    Returns: 0

  28. 585767164920993966

    644797924620882056

    Returns: 0

  29. 798057841747051409

    851841734813461339

    Returns: 0

  30. 749070736374533801

    811873140226833474

    Returns: 128

  31. 91972593928314415

    929437714725840724

    Returns: 512

  32. 54102594705839685

    971864155292650155

    Returns: 768

  33. 17438115591720206

    979807977131137619

    Returns: 1024

  34. 25080559573987391

    948391076642202451

    Returns: 1024

  35. 68493245237374770

    935282044706615984

    Returns: 768

  36. 20418497480925976

    985179090453708307

    Returns: 1024

  37. 52794849364031515

    978499011279142317

    Returns: 768

  38. 85767164920993966

    944797924620881899

    Returns: 512

  39. 51841734813461339

    998057841747051331

    Returns: 768

  40. 49070736374533801

    911873140226833355

    Returns: 768

  41. 1

    1000000000000000000

    Returns: 2044

  42. 4

    777777777777777777

    Returns: 2044

  43. 7

    444444444444444444

    Returns: 1532

  44. 5

    536417038372758858

    Returns: 1787

  45. 8

    665213705816950778

    Returns: 1786

  46. 5

    461882560036164617

    Returns: 1659

  47. 5

    502858337351765142

    Returns: 1787

  48. 4774747444747774

    9284387456984365

    Returns: 150

  49. 11

    999999999999999999

    Returns: 2042

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