1680. Concatenation of Consecutive Binary Numbers

https://leetcode.com/problems/concatenation-of-consecutive-binary-numbers

Description

Given an integer n, return the decimal value of the binary string formed by concatenating the binary representations of 1 to n in order, modulo 109 + 7.

Example 1:

**Input:** n = 1
**Output:** 1
**Explanation:** "1" in binary corresponds to the decimal value 1. 

Example 2:

**Input:** n = 3
**Output:** 27
**Explanation:** In binary, 1, 2, and 3 corresponds to "1", "10", and "11".
After concatenating them, we have "11011", which corresponds to the decimal value 27.

Example 3:

**Input:** n = 12
**Output:** 505379714
**Explanation**: The concatenation results in "1101110010111011110001001101010111100".
The decimal value of that is 118505380540.
After modulo 109 + 7, the result is 505379714.

Constraints:

• 1 <= n <= 105

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