poj3304

maksyuki 发表于 oj 分类,标签:
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Segments

Given n segments in the two dimensional space, write a program, which determines if there exists a line such that after projecting these segments on it, all projected segments have at least one point in 阅读全文 »

TopCoder SRM#677(Div2)(2/3)

maksyuki 发表于 比赛 分类,标签:
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250 Problem Statement

A positive integer is called a prime if it has exactly two distinct positive integer divisors: 1 and itself. The first few primes are 2, 3, 5, 7, 11, 13, ...

A positive integer is called a palindrome if its base-10 representation reads the same forwards and backwards. Some palindromes: 2, 77, 101, 33333, 12344321.

A positive integer is called a palindromic prime if it is both a palindrome and a prime.

You are given two ints: L and R. Compute and return the number of palindromic primes between L and R, inclusive.
Definition
Class: PalindromePrime
Method: count
Parameters: int, int
Returns: int
Method signature: int count(int L, int R)
(be sure your method is public)

 

题目类型:暴力枚举

算法分析:直接循环枚举判断即可

 

550 Problem Statement

We have four strings: a, b, c, and d.

A superstring of our four strings is any string S such that each of the four strings occurs somewhere in S as a contiguous substring. Note that some superstrings of our four strings always exist.

For example, the string S = a+b+c+d is obviously a superstring of a, b, c, and d.

Find and return the length of the shortest superstring of a, b, c, and d.
Definition
Class: FourStrings
Method: shortestLength
Parameters: string, string, string, string
Returns: int
Method signature: int shortestLength(string a, string b, string c, string d)
(be sure your method is public)

 

题目类型:暴力枚举+判断

算法分析:由于一共才有4!种排列,所以可以使用next_permutation函数来生成每个排列,然后先判断当前字符串si是否是res的子串,若是则直接判断下一个字符串si+1。否则枚举res后min(res_len, si_len) ~ 0个子串并和si的前len ~ 0个子串比较。将多出来的部分加到res的尾部。最后统计最小值即可

 

poj3592

maksyuki 发表于 oj 分类,标签: ,
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Instantaneous Transference

It was long ago when we played the game Red Alert. There is a magic function for the game objects which is called instantaneous transfer. When an object uses this magic function, it will be transferred to the specified point immediately, regardless of how far it is.

Now there is a mining area, and you are driving an ore-miner truck. Your mission is to take the maximum ores in the field.

The ore area is a rectangle region which is composed by n × m small squares, some of the squares have numbers of ores, while some do not. The ores can't be regenerated after taken.

The starting position of the ore-miner truck is the northwest corner of the field. It must move to the eastern or southern adjacent square, while it can not move to the northern or western adjacent square. And some squares have magic power that can instantaneously transfer the truck to a certain square specified. However, as the captain of the ore-miner truck, you can decide whether to use this magic power or to stay still. One magic power square will never lose its magic power; you can use the magic power whenever you get there.

Input

The first line of the input is an integer T which indicates the number of test cases.

For each of the test case, the first will be two integers NM (2 ≤ NM ≤ 40).

The next N lines will describe the map of the mine field. Each of the N lines will be a string that contains M characters. Each character will be an integer X (0 ≤ X ≤ 9) or a '*' or a '#'. The integer X indicates that square has X units of ores, which your truck could get them all. The '*' indicates this square has a magic power which can transfer truck within an instant. The '#' indicates this square is full of rock and the truck can't move on this square. You can assume that the starting position of the truck will never be a '#' square.

As the map indicates, there are K '*' on the map. Then there follows K lines after the map. The next K lines describe the specified target coordinates for the squares with '*', in the order from north to south then west to east. (the original point is the northwest corner, the coordinate is formatted as north-south, west-east, all from 0 to N - 1,- 1).

Output

For each test case output the maximum units of ores you can take.

Sample Input

1

2 2

11

1*

0 0

Sample Output

3

Source

South Central China 2008 hosted by NUDT

 

题目类型:有向图强连通分量+缩点+树形DP

算法分析:每个非”#”点和左边、下边的点之间连一条有向边,若遇到”#”点则不连,当然需要将平面图的坐标重新映射一下。对于每个魔法点”*”,需要额外判断是否能够向其目标点连有向边(目标点非”#”才能连)。易知同一个强连通分量中的点可以双向可达,所以可以缩点,用其中所有点的val值的和来表示缩点后的点的点权,缩点后的图是一个有向无环图且没有重边,所以可以看做是树。使用dp[i]表示以i为根的子树所具有的最大价值。dp[i]初始化成对应缩点后的点权。状态转移方程为dp[u] = max (dp[u], vval[u] + dp[v]),vval[u]表示u点处的点权(缩点后)且v是u的子节点。最后输出顶点1所在缩点处的dp值即可

 

poj1904

maksyuki 发表于 oj 分类,标签: ,
0

King's Quest

Once upon a time there lived a king and he had N sons. And there were N beautiful girls in the kingdom and the king knew about each of his sons which of those girls he did like. The sons of the king were young and light-headed, so it was possible for one son to like several girls.

So the king asked his wizard to find for each of his sons the girl he liked, so that he could marry her. And the king's wizard did it -- for each son the girl that he could marry was chosen, so that he liked this girl and, of course, each beautiful girl had to marry only one of the king's sons.

However, the king looked at the list and said: "I like the list you have made, but I am not completely satisfied. For each son I would like to know all the girls that he can marry. Of course, after he marries any of those girls, for each other son you must still be able to choose the girl he likes to marry."

The problem the king wanted the wizard to solve had become too hard for him. You must save wizard's head by solving this problem.

Input

The first line of the input contains N -- the number of king's sons (1 <= N <= 2000). Next N lines for each of king's sons contain the list of the girls he likes: first Ki -- the number of those girls, and then Ki different integer numbers, ranging from 1 to N denoting the girls. The sum of all Ki does not exceed 200000.

The last line of the case contains the original list the wizard had made -- N different integer numbers: for each son the number of the girl he would marry in compliance with this list. It is guaranteed that the list is correct, that is, each son likes the girl he must marry according to this list.

Output

Output N lines.For each king's son first print Li -- the number of different girls he likes and can marry so that after his marriage it is possible to marry each of the other king's sons. After that print Li different integer numbers denoting those girls, in ascending order.

Sample Input

4
2 1 2
2 1 2
2 2 3
2 3 4
1 2 3 4

Sample Output

2 1 2

2 1 2

1 3

1 4

Hint

This problem has huge input and output data,use scanf() and printf() instead of cin and cout to read data to avoid time limit exceed.

Source

Northeastern Europe 2003

 

题目类型:有向图强连通分量(二分图完备匹配)

算法分析:这道题直观上是一道求解二分图完备匹配并输出所有满足条件的问题。但是由于顶点数和边数比较多,所以直接使用找增广链的算法会超时。这里利用二分图完备匹配的性质来简化问题。如何才能不通过寻找增广链而直接确定是否存在增广链呢?让我们再次回到初始的想法,如果给定的完备匹配中xi -> yi,现在我们想让xi指向yj。如果让xi -> yj的话,那么yi显然对于xi已经没用了,又因为最终的匹配必然是一个完备匹配,即yi一定会被某一个xk(1 <= k <= n)所匹配。所以假如寻找到了增广链,那么增广链的最后一条边所指向的顶点必然是yi。假如我们由yi向xi再连一条边会发生什么呢? 很明显,形成了一个环!也就是说,形成了一个强连通分量。所以说,如果xi可以选择yj(即xi喜欢yi且可以结婚),那么xi和yj必然属于同一个强连通分量。所以此题可用强连通分量来求解,求解出强连通分量后直接统计即可