921. 最少插入使括号有效
原文英文,约500词,阅读约需2分钟。发表于: 。921. Minimum Add to Make Parentheses Valid Difficulty: Medium Topics: String, Stack, Greedy A parentheses string is valid if and only if: It is the empty string, It can be written as AB (A...
给定一个括号字符串,通过最少插入操作使其有效。遍历字符串时,用`balance`记录括号平衡,`additions`记录需要插入的括号数。当`balance`为负时,增加`additions`并重置`balance`。遍历结束后,若`balance`大于0,将其加到`additions`。时间复杂度为O(n),空间复杂度为O(1)。