g3601_3700.s3621_number_of_integers_with_popcount_depth_equal_to_k_i.Solution

public class Solution extends Object

3621 - Number of Integers With Popcount-Depth Equal to K I.

Hard

You are given two integers n and k.

For any positive integer x, define the following sequence:

p₀ = x
p_i+1 = popcount(p_i) for all i >= 0, where popcount(y) is the number of set bits (1’s) in the binary representation of y.

This sequence will eventually reach the value 1.

The popcount-depth of x is defined as the smallest integer d >= 0 such that p_d = 1.

For example, if x = 7 (binary representation "111"). Then, the sequence is: 7 \u2192 3 \u2192 2 \u2192 1, so the popcount-depth of 7 is 3.

Your task is to determine the number of integers in the range [1, n] whose popcount-depth is exactly equal to k.

Return the number of such integers.

Example 1:

Input: n = 4, k = 1

Output: 2

Explanation:

The following integers in the range [1, 4] have popcount-depth exactly equal to 1:

x	Binary	Sequence
2	`"10"`	`2 \u2192 1`
4	`"100"`	`4 \u2192 1`

Thus, the answer is 2.

Example 2:

Input: n = 7, k = 2

Output: 3

Explanation:

The following integers in the range [1, 7] have popcount-depth exactly equal to 2:

Thus, the answer is 3.

Constraints:

Constructor Details
- Solution
  
  public Solution()
Method Details
- popcountDepth
  
  public long popcountDepth(long tillNumber, int depthQuery)

Class Solution

Constructor Summary