Package g1901_2000.s1987_number_of_unique_good_subsequences

Class Solution

  • public class Solution
extends Object
    1987 - Number of Unique Good Subsequences.

    Hard

    You are given a binary string binary. A subsequence of binary is considered good if it is not empty and has no leading zeros (with the exception of "0").

    Find the number of unique good subsequences of binary.

    • For example, if binary = "001", then all the good subsequences are ["0", "0", "1"], so the unique good subsequences are "0" and "1". Note that subsequences "00", "01", and "001" are not good because they have leading zeros.

    Return the number of unique good subsequences of binary. Since the answer may be very large, return it modulo 109 + 7.

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

    Example 1:

    Input: binary = “001”

    Output: 2

    Explanation: The good subsequences of binary are [“0”, “0”, “1”].

    The unique good subsequences are “0” and “1”.

    Example 2:

    Input: binary = “11”

    Output: 2

    Explanation: The good subsequences of binary are [“1”, “1”, “11”].

    The unique good subsequences are “1” and “11”.

    Example 3:

    Input: binary = “101”

    Output: 5

    Explanation: The good subsequences of binary are [“1”, “0”, “1”, “10”, “11”, “101”].

    The unique good subsequences are “0”, “1”, “10”, “11”, and “101”.

    Constraints:

    • 1 <= binary.length <= 105
    • binary consists of only '0's and '1's.

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • numberOfUniqueGoodSubsequences

        public int numberOfUniqueGoodSubsequences​(String binary)