// Package q1680 implements a solution for https://leetcode.com/problems/concatenation-of-consecutive-binary-numbers/
package q1680

const MOD int = 1e9 + 7

func concatenatedBinary(n int) int {
	ret := 0
	binLen := 1

	for c := 1; c <= n; c++ {
		if 1<<binLen <= c {
			binLen++
		}

		ret = (ret<<binLen + c) % MOD
	}
	return ret
}

var _ = concatenatedBinary