Problem Statement
John thinks 4 and 7 are lucky digits, and all other digits are not lucky. A lucky number is a number that contains only lucky digits in decimal notation.
You are given an
Definition
- Class:
- TheLargestLuckyNumber
- Method:
- find
- Parameters:
- int
- Returns:
- int
- Method signature:
- int find(int n)
- (be sure your method is public)
Constraints
- n will be between 4 and 1,000,000, inclusive.
Examples
100
Returns: 77
77 is the largest lucky number that is not greater than 100.
75
Returns: 74
74 is the lucky number that immediately precedes 77.
5
Returns: 4
The smallest lucky number is 4.
474747
Returns: 474747
n is a lucky number.
1000000
Returns: 777777
45
Returns: 44
71
Returns: 47
38
Returns: 7
4
Returns: 4
73
Returns: 47
1041
Returns: 777
1467
Returns: 777
1334
Returns: 777
1500
Returns: 777
1169
Returns: 777
100041
Returns: 77777
118467
Returns: 77777
106334
Returns: 77777
126500
Returns: 77777
119169
Returns: 77777
900041
Returns: 777777
918467
Returns: 777777
906334
Returns: 777777
926500
Returns: 777777
919169
Returns: 777777
447749
Returns: 447747
477
Returns: 477
747800
Returns: 747777
777444
Returns: 777444
444777
Returns: 444777
747473
Returns: 747447
747475
Returns: 747474
747479
Returns: 747477
27
Returns: 7
686886
Returns: 477777
234908
Returns: 77777
44
Returns: 44
57
Returns: 47
70
Returns: 47
433
Returns: 77
9800
Returns: 7777
11
Returns: 7
432345
Returns: 77777
147
Returns: 77
4274
Returns: 777
900005
Returns: 777777
9801
Returns: 7777
55555
Returns: 47777
72
Returns: 47