Problem Description: FJ is about to take his N (1 <= N <= 30,000) cows to the annual “Farmer of the Year” competition. In this contest every farmer arranges his cows in a line and herds them past the judges. The contest organizers adopted a new registration scheme this year: simply register the initial letter […]

# Category: OI

## AtCoder Regular 099E: Independence

Problem Description: https://arc099.contest.atcoder.jp/tasks/arc099_c This problem is one that requires thoughts on complement graph. The official editorial has done a pretty good job in explanation. Step: Convert into complement graph -> Find characteristic of this graph -> Bipartite graph -> Convert back -> Find minimum roads -> DP #include <iostream> #include <cstring> #include <string> #include <vector> #include […]

## BZOJ4027: Rabbits and Sakura [HEOI2015]

Problem Description: You are given a sakura tree(try to be descriptive). At each node of the tree(actually a tree structure!), there is a weight and children nodes. The rabbits want to remove as many nodes as possible on the sakura tree(don’t know why) while following the several rules. For each node the rabbits remove, its […]

## BZOJ1556: The Secret of the Grave

Problem Description: You start at a point (sx,sy). There are T gravestones at on the map. You can destroy(diss joy?) a gravestone by touch the four sides that are adjacent to it. After destroying a gravestone, the gravestone turns into a wall, which you cannot pass through. As a Übermensch, you can move in one […]

## BZOJ3223: Artful SBT

Problem Description: Given a sequence comprised of numbers from 1 – N in order. There are M operations. Each operation will flip a sequence [l,r]. Please output the finally formed sequence. Input Format: One line with the number N and M. The next M lines contain two numbers l and r. Output Format: The sequence […]

## P2519: problem a [HAOI2011]

Problem Description: N students are in classroom, the ith student says there are students that have scores higher than me and students that have scores lower than me(There might exist same scores). Please give out the minimum possible number of students that are lying. Input Format: First line with one integer N ≤ 100000 Next […]

## HDU2896: Virus Infection

Problem Description: There are N computer viruses and M potential infected websites. Each virus and website can be described as a string. The task is to find which websites are infected by what kinds of viruses and the total number of infected websites with viruses. Input Format: The first line contains one number N. The […]

## P2153: Exercise [SDOI2009]

Problem Description: There are N nodes and M edges, you can go through each node at most once, there are weights on the edges. Try to minimize the total weight going through 1 to N while maximizing the times you can go from 1 to N without passing through any nodes twice except node 1 […]

## P2515: Software Installation [HAOI2010]

Problem Description: You have computer with M amount of storage. There are N softwares you are going to install on the computer. The ith computer takes amount of storage and has a value of . There are also dependencies between softwares. Specifically, the ith software can be installed only if is installed. Every software can be only installed once, […]

## BZOJ-1002: Rotavirus [FJOI2007]

Problem Description: There are many variety to the rotavirus. Some of them follow the structure in the image below(graph 1.1), where there are connections between every node on the circumference with the center and with its neighbour. Specifically, we define the N-sided virus as a virus that for every pairs of nodes on the virus […]