Rajesh loves lucky numbers. Everyone knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, the numbers 47,744, 4 are lucky and 5, 17,467 are not. Let F(x) equal the number of digits d in the decimal representation of the positive integer x. Chef is only interested in F4(x) and F7(x) functions. For a given positive integer N, he wants to know the total number of distinct pairs (L; R) such that F4(L) + F4(L + 1) + ... + F4(R) equals F7(L) + F7(L + 1) + ... + F7(R) and 1

Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
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Python only
Rajesh loves lucky numbers. Everyone knows that lucky numbers are positive integers whose
decimal representation contains only the lucky digits 4 and 7. For example, the numbers 47,744, 4
are lucky and 5, 17,467 are not.
Let Fa(x) equal the number of digits d in the decimal representation of the positive integer x. Chef is
only interested in F4(x) and F7(x) functions. For a given positive integer N, he wants to know the total
number of distinct pairs (L; R) such that F4(L) + F4(L + 1) + ... + F4(R) equals F7(L) + F7(L + 1) + ... + F7(R)
and 1 <L<R <N.
Input
1
10
Output
31
Transcribed Image Text:Python only Rajesh loves lucky numbers. Everyone knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, the numbers 47,744, 4 are lucky and 5, 17,467 are not. Let Fa(x) equal the number of digits d in the decimal representation of the positive integer x. Chef is only interested in F4(x) and F7(x) functions. For a given positive integer N, he wants to know the total number of distinct pairs (L; R) such that F4(L) + F4(L + 1) + ... + F4(R) equals F7(L) + F7(L + 1) + ... + F7(R) and 1 <L<R <N. Input 1 10 Output 31
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