不妨先操作一轮,使得$0\le a_{i}\le 2$ 结论:若序列中存在1,则答案为0或1 考虑归纳,注意到若序列中存在1,除非所有元素均为1,否则操作一轮后必然仍存在1,那么根据归纳假设即成立,而当所有元素均为1时,显然答案一定为0或1(序列长度已经为1),同样成立 由此,实际上只需要通过奇偶性即可确定答案,而注意到$|x-y|\equiv x+y(mod\ 2)$,因此不妨将转移的式子变为$a'_{i}=a_{i}+a_{i+1}$(模2意义下) 简单计数,不难发现$a_{i}$对答案的贡…

1043 - Triangle Partitioning PDF (English) Statistics Forum Time Limit: 0.5 second(s) Memory Limit: 32 MB See the picture below. You are given AB, AC and BC. DE is parallel to BC. You are also given the area ratio between ADE and BDEC. You have to fi…

1043 - Triangle Partitioning   PDF (English) Statistics Forum Time Limit: 0.5 second(s) Memory Limit: 32 MB See the picture below. You are given AB, AC and BC. DE is parallel to BC. You are also given the area ratio between ADE and BDEC. You have to…

12-3. 数据库连接日志 问题 你想为每次与数据库的连接和断开记录日志 解决方案 EF为DbContext的连接公开了一个StateChange 事件.我们需要处理这个事件, 为每次与数据库的连接和断开记录日志. 假设我们的模型如Figure 12-3所示. 在 Listing 12-3代码里, 我们创建一些Donation 实例,然后把它们保存到数据库. 这里的代码实现override SaveChanges() 方法为我们的StateChange 事件提供切入点. Figure 12-3.…

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below. For example, given the following triangle [ [], [,4], [6,,7], [4,,8,3] ] The minimum path sum from top to bottom is 11 (i.e.,…

Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3,Return [1,3,3,1]. Note:Could you optimize your algorithm to use only O(k) extra space? 杨辉三角想必大家并不陌生,应该最早出现在初高中的数学中,其实就是二项式系数的一种写法. 1 1 1 1 2 1 1 3 3 1 1 4 6 4 1 1…

Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5,Return [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ] 杨辉三角是二项式系数的一种写法,如果熟悉杨辉三角的五个性质,那么很好生成,可参见我的上一篇博文: http://www.cnblogs.com/grandyang/p/4031536.html 具体生…

题目简述: Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3, Return [1,3,3,1]. Note: Could you optimize your algorithm to use only O(k) extra space? 解题思路: 这里的关键是空间的使用,既然只能用O(K)很容易就想到我们要进行回卷(名字好像不对).我的做法是每一次都在后面新加入一个数…

题目简述: Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5, Return [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1]] 解题思路: 很简单的问题,只要把两头的一拿出来,中间就是两个数相加了. class Solution: # @return a list of lists of integers def…

http://poj.org/problem?id=1163 The Triangle Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 32923   Accepted: 19514 Description 73 88 1 02 7 4 44 5 2 6 5 (Figure 1) Figure 1 shows a number triangle. Write a program that calculates the hi…