Added task 2311.

Author: AryamanMishra

src/main/java/g2301_2400/s2311_longest_binary_subsequence_less_than_or_equal_to_k/Solution.java

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+package g2301_2400.s2311_longest_binary_subsequence_less_than_or_equal_to_k;
+
+// #Medium #Math #2022_06_20_Time_1_ms_(100.00%)_Space_42.3_MB_(50.00%)
+
+public class Solution {
+ public int longestSubsequence(String s, int k) {
+ int res = 0;
+ int cost = 1;
+ int n = s.length();
+ for (int i = n - 1; i >= 0; i--) {
+ if (s.charAt(i) == '0' || cost <= k) {
+ k -= cost * (s.charAt(i) - '0');
+ ++res;
+ }
+ if (cost <= k) {
+ cost *= 2;
+ }
+ }
+ return res;
+ }
+}

src/main/java/g2301_2400/s2311_longest_binary_subsequence_less_than_or_equal_to_k/readme.md

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+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 <= 10<sup>9</sup></code>

src/test/java/g2301_2400/s2311_longest_binary_subsequence_less_than_or_equal_to_k/SolutionTest.java

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+package g2301_2400.s2311_longest_binary_subsequence_less_than_or_equal_to_k;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class SolutionTest {
+ @Test
+ void longestSubsequence() {
+ assertThat(new Solution().longestSubsequence("1001010", 5), equalTo(5));
+ }
+
+ @Test
+ void longestSubsequence2() {
+ assertThat(new Solution().longestSubsequence("00101001", 1), equalTo(6));
+ }
+}