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Solution: Find The K-th Lucky Number

Understand how to find the k-th lucky number composed only of digits 4 and 7 by applying bitwise manipulation and binary representation techniques. This lesson guides you through converting an integer k into a lucky number string, explaining each step clearly and showing how to efficiently compute the result with optimal time and space complexity.

Statement

A number is called lucky if it comprises only the digits 44 and 77. Your task is to return the k-th lucky number as a string for a given integer k

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