Broken Necklace
You have a necklace of N red, white, or blue beads (3<=N<=350) some of which are red, others blue, and others white, arranged at random. Here are two examples for n=29:

           &nb[……]

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Controlling Companies 

Some companies are partial owners of other companies because they have acquired part of their total shares of stock. For example, Ford owns 12% of Mazda. It is said that a company A controls company B if at least one of the following co[......]
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The Tamworth Two 
BIO \'98 - Richard Forster 
A pair of cows is loose somewhere in the forest. Farmer John is lending his expertise to their capture. Your task is to model their behavior. 

The chase takes place on a 10 by 10 planar grid. Squares can be e[......]
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Cow Tours 
Farmer John has a number of pastures on his farm. Cow paths connect some pastures with certain other pastures, forming a field. But, at the present time, you can find at least two pastures that cannot be connected by any sequence of cow paths, thus[......]
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USACO 2.4 Overfencing 穿越栅栏 
Overfencing 
Kolstad and Schrijvers 
Farmer John went crazy and created a huge maze of fences out in a field. Happily, he left out two fence segments on the edges, and thus created two exits for the maze. Even more happily, the maze[......]
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USACO 2.2 Subset Sums集合
For many sets of consecutive integers from 1 through N (1 <= N <= 39), one can partition the set into two sets whose sums are identical.
For example, if N=3, one can partition the set {1, 2, 3} in one way so that the sums of both[……]

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Packing Rectangles 铺放矩形块 (IOI 95)

在网上看了挺多解释这一题的文章，总感觉没看大懂，所以自己写一篇文章吧。希望能够帮助大家理解一下这一题。题目如下：

http://www.nocow.cn/index.php/Translate:USACO/packrec

开始拿到题目确实没怎么看懂，网上也有很多人说它是个水题，我倒感觉不以为然，我看了一些网上的人写的代码，说它是水题的人都是怎么写的。整个程序框架就是第一种情况循环+判断，第二种情况循环+判断，…………（以此类推）

接下来我来说下我的[……]

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这题很简单，一位一位算就是，唯一要注意的就是mod 11 = 10的时候，要用X。代码：

C语言:

#include <stdio.h>
#include <ctype.h>
char isbn[14];

char getint(void)
{
 static int i = 0;
 int t;
 do{
 t = isbn[i++];
 }while(!isdigit(t));
 return t - \'0\';
}

int main(void)
{
 int[......]
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不知道这题该属于哪个类别，，贪心？枚举？反正不难，，代码：

C语言:

#include <stdio.h>

int main(void)
{
 int i;
 int a, b;
 int ans = 0, t = 0;
 for(i = 1; i <= 7; i++){
 scanf(%d%d, &a, &b);
 if((a + b > 8) && (a + b > t)){
 ans = i;
 t = a + b;
 }
 }
 printf([......]
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