3821. Find Nth Smallest Integer With K One Bits

You are given two positive integers n and k. Return an integer denoting the nth smallest positive integer that has exactly k ones in its binary representation. It is guaranteed that the answer is strictly less than 250. Example 1: Input: n = 4, k = 2 Output: 9 Explanation: The 4 smallest positive integers that have exactly k = 2 ones in their binary representations are: - 3 = 112 - 5 = 1