题目链接 题解(树状数组) 我们维护两个树状数组,一个记录 \(1\sim i\) 中 \(s_i>s_{i+1}\)的数量,即逆序对数量,另一个记录 \(1\sim i\) 中 \(26\) 个字母的数量. 在修改时很好维护,先把原来的字母数量减 \(1\) ,再新的字母数加 \(1\) ,逆序对以类似方式维护. 重点在查询,一个区间 \([l,r]\) 被包含在排序后的字符串中,当且仅当这个区间里没有逆序对(即统计逆序对数量的树状数组 \([l,r-1]\) ,注意,右端点是 \(r-1\)…

原题链接在这里:https://leetcode.com/problems/replace-the-substring-for-balanced-string/ 题目: You are given a string containing only 4 kinds of characters 'Q', 'W', 'E' and 'R'. A string is said to be balanced if each of its characters appears n/4 times where…

在String中有两个substring()函数,如下: 一:String.substring(int start) 参数: start:要截取位置的索引 返回: 从start开始到结束的字符串 例如:String str = "hello word!";         System.out.println(str.substring(1)); System.out.println(str.substring(3)); System.out.println(str.substring…

Longest Substring Without Repeating Characters: Given a string, find the length of the longest substring without repeating characters. Examples: Given "abcabcbb", the answer is "abc", which the length is 3. Given "bbbbb", the…

题目中文:求最长回文子串 题目难度:Medium 题目内容: Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. 翻译: 给定一个字符串s,找出s中最长的回文子串.你可以假设s的最大长度是1000. 什么叫回文子串? 就是字符串中,满足能正读反读都一样的子串,就是回文子串.如下所示 Input: "babad"…

题目如下: You are given a string containing only 4 kinds of characters 'Q', 'W', 'E' and 'R'. A string is said to be balanced if each of its characters appears n/4 times where n is the length of the string. Return the minimum length of the substring that…

题目 Given a string, find the length of the longest substring without repeating characters. Example 1: Input: "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. Example 2: Input: "bbbbb" Output: 1 Expl…

题目 题目 s = "3[a]2[bc]", return "aaabcbc". s = "3[a2[c]]", return "accaccacc". s = "2[abc]3[cd]ef", return "abcabccdcdcdef". 大概意思是根据指定的格式将字符串进行展开 思路 递归的思路 递归计算出括号最里面的字符串,依次再处理外面一层的字符串,每个单元内的字符串类似于一…

Remove Duplicates from Sorted Array: Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space for another array, you must do this in place with constant memory…

Leetcode Find Minimum in Rotated Sorted Array 题目大意: 对一个有序数组翻转, 就是随机取前K个数,移动到数组的后面,然后让你找出最小的那个数.注意,K有可能是0,也就是没有翻转. 毫无疑问,遍历一次肯定能够找到,但这样时间复杂度是O(n).假设你在面试的时候遇到这种问题,你这样回答面试官肯定不会惬意的.我们接下来讨论有没有什么更快的方法.O(nlogn)?? 我还是把O(N)的代码贴出来,不知道为什么leetcode上竟然不超时. //O(n) c…