Given a string, find the length of the longest substring T that contains at most k distinct characters. For example, Given s = “eceba” and k = 2, T is "ece" which its length is 3. 这道题是之前那道Longest Substring with At Most Two Distinct Characters的拓展…
Given a string S, find the length of the longest substring T that contains at most two distinct characters.For example,Given S = “eceba”,T is “ece” which its length is 3. 这道题给我们一个字符串,让我们求最多有两个不同字符的最长子串.那么我们首先想到的是用哈希表来做,哈希表记录每个字符的出现次数,然后如果哈希表中的映射数量超过两…
Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative…
SQL中distinct的用法 1.作用于单列 2.作用于多列 3.COUNT统计 4.distinct必须放在开头 5.其他 在表中,可能会包含重复值.这并不成问题,不过,有时您也许希望仅仅列出不同(distinct)的值.关键词 distinct用于返回唯一不同的值. 表A: 表B: 1.作用于单列 select distinct name from A 执行后结果如下: 2.作用于多列 示例2.1 select distinct name, id from A 执行后结果如下: 实际上…
https://leetcode.com/problems/distinct-subsequences/ Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be non…
例如下表格:表名:fruit id Name Price Num 1 西瓜 10 2 2 西瓜 11 2 3 香蕉 10 3 4 桃子 10 2 当我想获取Name不重复的数据,结果如下 id Name Price Num 1 西瓜 10 2 3 香蕉 10 3 4 桃子 10 2 如果查询时用 distinct,则无效果,只能用group by. select * from fruit where id in (select min(id) from fruit group by Name)…
