I caught the sparkle in my mind and got AC1 ! It is a great great experience ! So the basic idea: permute on 3 consecutive items doesn't change the parity of the no. of inversions. Each permutation can only remove 0 or 2 inversions. So we say "YES&qu…

1 简介 不得不说,Spring为大家提供许多开箱即用的功能,@Value就是一个极其常用的功能,它能将配置信息注入到bean中去.即使是一个简单的功能,Spring也提供了丰富的注入类型和形式.我经常会忘记一些特别类型注入的写法,比如说数组,现在整理一下,希望以后不用再找了. 2 三种形式 使用@Value注入有三种形式,如下所示: (1)直接写值@Value("string value") 这种方式就是直接把要注入的值字面量写在注解里,比较少用.如果要写死在注解里了,那直接定义变量…

The most interesting, flexible and juicy binary tree problem I have ever seen. I learnt it from here: https://codepair.hackerrank.com/paper/5fIoGg74?b=eyJyb2xlIjoiY2FuZGlkYXRlIiwibmFtZSI6IkJsdWVCaXJkMjI0IiwiZW1haWwiOiJoZWFsdGh5dG9ueUBnbWFpbC5jb20ifQ%…

Watson gives an array A1,A2...AN to Sherlock. Then he asks him to find if there exists an element in the array, such that, the sum of elements on its left is equal to the sum of elements on its right. If there are no elements to left/right, then sum…

list.set.map.array间的相互转换 list转set Set set = new HashSet(new ArrayList()); set转list List list = new ArrayList(new HashSet()); array转为list List stooges = Arrays.asList("Larry", "Moe", "Curly"); 或者 String[] arr = {"1",…

This is 'Difficult' - I worked out it within 45mins, and unlocked HackerRank Algorithm Level 80 yeah! So the idea is straight forward: 1. sort the input array and calculate partial_sum()2. find the negative\positive boundary with the accumulated give…

1 数组转换为List 调用Arrays类的静态方法asList. asList public static <T> List<T> asList(T... a) Returns a fixed-size list backed by the specified array. (Changes to the returned list "write through" to the array.) This method acts as bridge betwee…

题目链接:Running Time of Quicksort Challenge In practice, how much faster is Quicksort (in-place) than Insertion Sort? Compare the running time of the two algorithms by counting how many swaps or shifts each one takes to sort an array, and output the dif…

简说排序 排序是极其常见的使用场景,因为在生活中就有很多这样的实例.国家GDP排名.奥运奖牌排名.明星粉丝排名等,各大排行榜,给人的既是动力,也是压力. 而讲到排序,就会有各种排序算法和相关实现,本文不讲任何排序算法,而只专注于讲使用.通过实例给大家展示,我们可以了解怎样使用既有的工具进行排序.Linux之父说: Talk is cheap. show me the code! 本文JDK版本为Java 8,但并不代表所介绍到的所有方法只能在JDK1.8上跑,部分方法在之前的版本就已经给出. 如…

https://www.hackerrank.com/challenges/minimum-swaps-2/problem Minimum Swaps II You are given an unordered array consisting of consecutive integers  [1, 2, 3, ..., n] without any duplicates. You are allowed to swap any two elements. You need to find t…