摘要： SudokuTime Limit:2000MSMemory Limit:65536KTotal Submissions:12818Accepted:6381Special JudgeDescriptionSudoku is a very simple task. A square table with 9 rows and 9 columns is divided to 9 smaller squares 3x3 as shown on the Figure. In some of the cells are written decimal digits from 1 to 9. The ot 阅读全文

摘要： Cow PicnicTime Limit:2000MSMemory Limit:65536KTotal Submissions:4928Accepted:2019DescriptionThe cows are having a picnic! Each of Farmer John'sK(1 ≤K≤ 100) cows is grazing in one ofN(1 ≤N≤ 1,000) pastures, conveniently numbered 1...N. The pastures are connected byM(1 ≤M≤ 10,000) one-way paths (n 阅读全文

摘要： 滑雪Time Limit:1000MSMemory Limit:65536KTotal Submissions:71659Accepted:26468DescriptionMichael喜欢滑雪百这并不奇怪， 因为滑雪的确很刺激。可是为了获得速度，滑的区域必须向下倾斜，而且当你滑到坡底，你不得不再次走上坡或者等待升降机来载你。Michael想知道载一个区域中最长底滑坡。区域由一个二维数组给出。数组的每个数字代表点的高度。下面是一个例子 1 2 3 4 516 17 18 19 615 24 25 20 714 23 22 21 813 12 11 10 9一个人可以从某个点滑向上下左右相... 阅读全文

摘要： Prime PathTime Limit:1000MSMemory Limit:65536KTotal Submissions:10370Accepted:5922DescriptionThe ministers of the cabinet were quite upset by the message from the Chief of Security stating that they would all have to change the four-digit room numbers on their offices.— It is a matter of security to 阅读全文

摘要： Fiber NetworkTime Limit:1000MSMemory Limit:65536KTotal Submissions:2896Accepted:1335DescriptionSeveral startup companies have decided to build a better Internet, called the "FiberNet". They have already installed many nodes that act as routers all around the world. Unfortunately, they star 阅读全文

摘要： Big Christmas TreeTime Limit:3000MSMemory Limit:131072KTotal Submissions:20034Accepted:4304DescriptionChristmas is coming to KCM city. Suby the loyal civilian in KCM city is preparing a big neat Christmas tree. The simple structure of the tree is shown in right picture.The tree can be represented as 阅读全文

摘要： 求最短路径的算法有许多种，除了排序外，恐怕是ACM界中解决同一类问题算法最多的了。最熟悉的无疑是Dijkstra，接着是Bellman-Ford，它们都可以求出由一个源点向其他各点的最短路径；如果我们想要求出每一对顶点之间的最短路径的话，还可以用Floyd-Warshall。SPFA是这篇日志要写的一种算法，它的性能非常好，代码实现也并不复杂。特别是当图的规模大，用邻接矩阵存不下的时候，用SPFA则可以很方便地面对临接表。每个人都写过广搜，SPFA的实现和广搜非常相似。如何求得最短路径的长度值？首先说明，SPFA是一种单源最短路径算法，所以以下所说的“某点的最短路径长度”，指的是“某点到源点的 阅读全文