2311 - Longest Binary Subsequence Less Than or Equal to K.

Medium

You are given a binary string s and a positive integer k.

Return the length of the longest subsequence of s that makes up a binary number less than or equal to k.

Note:

• The subsequence can contain leading zeroes.

• The empty string is considered to be equal to 0.

• A subsequence is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.

Example 1:

Input: s = "1001010", k = 5

Output: 5

Explanation: The longest subsequence of s that makes up a binary number less than or equal to 5 is "00010", as this number is equal to 2 in decimal.

Note that "00100" and "00101" are also possible, which are equal to 4 and 5 in decimal, respectively.

The length of this subsequence is 5, so 5 is returned.

Example 2:

Input: s = "00101001", k = 1

Output: 6

Explanation: "000001" is the longest subsequence of s that makes up a binary number less than or equal to 1, as this number is equal to 1 in decimal.

The length of this subsequence is 6, so 6 is returned.

Constraints:

• 1 <= s.length <= 1000

• s[i] is either '0' or '1'.

• <code>1 <= k <= 10⁹</code>