{ "data": { "question": { "questionId": "1756", "questionFrontendId": "1653", "categoryTitle": "Algorithms", "boundTopicId": 481396, "title": "Minimum Deletions to Make String Balanced", "titleSlug": "minimum-deletions-to-make-string-balanced", "content": "

You are given a string s consisting only of characters 'a' and 'b'​​​​.

\n\n

You can delete any number of characters in s to make s balanced. s is balanced if there is no pair of indices (i,j) such that i < j and s[i] = 'b' and s[j]= 'a'.

\n\n

Return the minimum number of deletions needed to make s balanced.

\n\n

 

\n

Example 1:

\n\n
\nInput: s = "aababbab"\nOutput: 2\nExplanation: You can either:\nDelete the characters at 0-indexed positions 2 and 6 ("aababbab" -> "aaabbb"), or\nDelete the characters at 0-indexed positions 3 and 6 ("aababbab" -> "aabbbb").\n
\n\n

Example 2:

\n\n
\nInput: s = "bbaaaaabb"\nOutput: 2\nExplanation: The only solution is to delete the first two characters.\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": "使字符串平衡的最少删除次数", "translatedContent": "

给你一个字符串 s ，它仅包含字符 'a' 和 'b'​​​​ 。

\n\n

你可以删除 s 中任意数目的字符，使得 s 平衡 。我们称 s 平衡的 当不存在下标对 (i,j) 满足 i < j 且 s[i] = 'b' 同时 s[j]= 'a' 。

\n\n

请你返回使 s 平衡 的 最少 删除次数。

\n\n

 

\n\n

示例 1：

\n\n
\n输入：s = \"aababbab\"\n输出：2\n解释：你可以选择以下任意一种方案：\n下标从 0 开始，删除第 2 和第 6 个字符（\"aababbab\" -> \"aaabbb\"），\n下标从 0 开始，删除第 3 和第 6 个字符（\"aababbab\" -> \"aabbbb\"）。\n
\n\n

示例 2：

\n\n
\n输入：s = \"bbaaaaabb\"\n输出：2\n解释：唯一的最优解是删除最前面两个字符。\n
\n\n

 

\n\n

提示：

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