Package g1901_2000.s1987_number_of_unique_good_subsequences

Class Solution

java.lang.Object

g1901_2000.s1987_number_of_unique_good_subsequences.Solution

public class Solution
extends Object

1987 - Number of Unique Good Subsequences.<p>Hard</p> <p>You are given a binary string <code>binary</code>. A <strong>subsequence</strong> of <code>binary</code> is considered <strong>good</strong> if it is <strong>not empty</strong> and has <strong>no leading zeros</strong> (with the exception of <code>&quot;0&quot;</code>).</p> <p>Find the number of <strong>unique good subsequences</strong> of <code>binary</code>.</p> <ul> <li>For example, if <code>binary = &quot;001&quot;</code>, then all the <strong>good</strong> subsequences are <code>[&quot;0&quot;, &quot;0&quot;, &quot;1&quot;]</code>, so the <strong>unique</strong> good subsequences are <code>&quot;0&quot;</code> and <code>&quot;1&quot;</code>. Note that subsequences <code>&quot;00&quot;</code>, <code>&quot;01&quot;</code>, and <code>&quot;001&quot;</code> are not good because they have leading zeros.</li> </ul> <p>Return <em>the number of <strong>unique good subsequences</strong> of</em> <code>binary</code>. Since the answer may be very large, return it <strong>modulo</strong> <code>10⁹ + 7</code>.</p> <p>A <strong>subsequence</strong> is a sequence that can be derived from another sequence by deleting some or no elements without changing the order of the remaining elements.</p> <p><strong>Example 1:</strong></p> <p><strong>Input:</strong> binary = &ldquo;001&rdquo;</p> <p><strong>Output:</strong> 2</p> <p><strong>Explanation:</strong> The good subsequences of binary are [&ldquo;0&rdquo;, &ldquo;0&rdquo;, &ldquo;1&rdquo;].</p> <p>The unique good subsequences are &ldquo;0&rdquo; and &ldquo;1&rdquo;.</p> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> binary = &ldquo;11&rdquo;</p> <p><strong>Output:</strong> 2</p> <p><strong>Explanation:</strong> The good subsequences of binary are [&ldquo;1&rdquo;, &ldquo;1&rdquo;, &ldquo;11&rdquo;].</p> <p>The unique good subsequences are &ldquo;1&rdquo; and &ldquo;11&rdquo;.</p> <p><strong>Example 3:</strong></p> <p><strong>Input:</strong> binary = &ldquo;101&rdquo;</p> <p><strong>Output:</strong> 5</p> <p><strong>Explanation:</strong> The good subsequences of binary are [&ldquo;1&rdquo;, &ldquo;0&rdquo;, &ldquo;1&rdquo;, &ldquo;10&rdquo;, &ldquo;11&rdquo;, &ldquo;101&rdquo;].</p> <p>The unique good subsequences are &ldquo;0&rdquo;, &ldquo;1&rdquo;, &ldquo;10&rdquo;, &ldquo;11&rdquo;, and &ldquo;101&rdquo;.</p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= binary.length <= 10⁵</code></li> <li><code>binary</code> consists of only <code>'0'</code>s and <code>'1'</code>s.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	numberOfUniqueGoodSubsequences(String binary)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

numberOfUniqueGoodSubsequences

public int numberOfUniqueGoodSubsequences(String binary)