{ "data": { "question": { "questionId": "2027", "questionFrontendId": "1898", "categoryTitle": "Algorithms", "boundTopicId": 820334, "title": "Maximum Number of Removable Characters", "titleSlug": "maximum-number-of-removable-characters", "content": "
You are given two strings s
and p
where p
is a subsequence of s
. You are also given a distinct 0-indexed integer array removable
containing a subset of indices of s
(s
is also 0-indexed).
You want to choose an integer k
(0 <= k <= removable.length
) such that, after removing k
characters from s
using the first k
indices in removable
, p
is still a subsequence of s
. More formally, you will mark the character at s[removable[i]]
for each 0 <= i < k
, then remove all marked characters and check if p
is still a subsequence.
Return the maximum k
you can choose such that p
is still a subsequence of s
after the removals.
A subsequence of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.
\n\n\n
Example 1:
\n\n\nInput: s = "abcacb", p = "ab", removable = [3,1,0]\nOutput: 2\nExplanation: After removing the characters at indices 3 and 1, "a\n\nbcacb" becomes "accb".\n"ab" is a subsequence of "accb".\nIf we remove the characters at indices 3, 1, and 0, "abcacb" becomes "ccb", and "ab" is no longer a subsequence.\nHence, the maximum k is 2.\n
Example 2:
\n\n\nInput: s = "abcbddddd", p = "abcd", removable = [3,2,1,4,5,6]\nOutput: 1\nExplanation: After removing the character at index 3, "abc\n\nbddddd" becomes "abcddddd".\n"abcd" is a subsequence of "abcddddd".\n
Example 3:
\n\n\nInput: s = "abcab", p = "abc", removable = [0,1,2,3,4]\nOutput: 0\nExplanation: If you remove the first index in the array removable, "abc" is no longer a subsequence.\n\n\n
\n
Constraints:
\n\n1 <= p.length <= s.length <= 105
0 <= removable.length < s.length
0 <= removable[i] < s.length
p
is a subsequence of s
.s
and p
both consist of lowercase English letters.removable
are distinct.给你两个字符串 s
和 p
,其中 p
是 s
的一个 子序列 。同时,给你一个元素 互不相同 且下标 从 0 开始 计数的整数数组 removable
,该数组是 s
中下标的一个子集(s
的下标也 从 0 开始 计数)。
请你找出一个整数 k
(0 <= k <= removable.length
),选出 removable
中的 前 k
个下标,然后从 s
中移除这些下标对应的 k
个字符。整数 k
需满足:在执行完上述步骤后, p
仍然是 s
的一个 子序列 。更正式的解释是,对于每个 0 <= i < k
,先标记出位于 s[removable[i]]
的字符,接着移除所有标记过的字符,然后检查 p
是否仍然是 s
的一个子序列。
返回你可以找出的 最大 k
,满足在移除字符后 p
仍然是 s
的一个子序列。
字符串的一个 子序列 是一个由原字符串生成的新字符串,生成过程中可能会移除原字符串中的一些字符(也可能不移除)但不改变剩余字符之间的相对顺序。
\n\n\n\n
示例 1:
\n\n\n输入:s = \"abcacb\", p = \"ab\", removable = [3,1,0]\n输出:2\n解释:在移除下标 3 和 1 对应的字符后,\"abcacb\" 变成 \"accb\" 。\n\"ab\" 是 \"accb\" 的一个子序列。\n如果移除下标 3、1 和 0 对应的字符后,\"abcacb\" 变成 \"ccb\" ,那么 \"ab\" 就不再是 s 的一个子序列。\n因此,最大的 k 是 2 。\n\n\n
示例 2:
\n\n\n输入:s = \"abcbddddd\", p = \"abcd\", removable = [3,2,1,4,5,6]\n输出:1\n解释:在移除下标 3 对应的字符后,\"abcbddddd\" 变成 \"abcddddd\" 。\n\"abcd\" 是 \"abcddddd\" 的一个子序列。\n\n\n
示例 3:
\n\n\n输入:s = \"abcab\", p = \"abc\", removable = [0,1,2,3,4]\n输出:0\n解释:如果移除数组 removable 的第一个下标,\"abc\" 就不再是 s 的一个子序列。\n\n\n
\n\n
提示:
\n\n1 <= p.length <= s.length <= 105
0 <= removable.length < s.length
0 <= removable[i] < s.length
p
是 s
的一个 子字符串s
和 p
都由小写英文字母组成removable
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