SumOfLuckiness
SRM 526 · 2011-05-25 · by fushar
SRM 526 · 2011-05-25 · by fushar · Search, Simple Math
Problem Statement
Problem Statement
Mr. Dengklek once told you that 4 and 7 are lucky numbers. He also defined the luckiness of a positive integer as the absolute difference between the number of 7s in its decimal representation and the number of 4s in its decimal representation. For example, for each of the numbers 23, 47 and 47714 the luckiness is 0, and for each of the numbers 4474 and 7070 the luckiness is 2.
You are given twoint s A and B. Return the sum of luckiness of all integers between A and B, inclusive.
You are given two
Constraints
- A will be between 1 and 2,000,000,000, inclusive.
- B will be between A and 2,000,000,000, inclusive.
Examples
0)
1 10 Returns: 2
The luckiness of 4 is 1. The luckiness of 7 is 1. The luckiness of the other numbers is 0. So, the sum of luckiness is 2.
1)
40 47 Returns: 8
The luckiness of 40, 41, 42, 43, 45, and 46 is 1. The luckiness of 44 is 2. The luckiness of 47 is 0.
2)
58 526 Returns: 231
3)
4444 7777 Returns: 2338
4)
585858585 858585858 Returns: 287481025
Submissions are judged against all 44 archived test cases, of which 5 are shown here. Case numbers match the judge’s.
Coding Area
Language: C++17 · define a public class SumOfLuckiness with a public method long long theSum(int A, int B) · 44 test cases · 2 s / 256 MB per case