随笔分类 - ACM-USACO
摘要：Humble NumbersFor a given set of K prime numbers S = {p1, p2, ..., pK}, consider the set of all numbers whose prime factors are a subset of S. This set contains, for example, p1, p1p2, p1p1, and p1p2p3(among others). This is the set of `humble numbers' for the input set S. Note: The number 1 is
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摘要：Score InflationThe more points students score in our contests, the happier we here at the USACO are. We try to design our contests so that people can score as many points as possible, and would like your assistance.We have several categories from which problems can be chosen, where a "category&
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摘要：Agri-NetRuss CoxFarmer John has been elected mayor of his town! One of his campaign promises was to bring internet connectivity to all farms in the area. He needs your help, of course.Farmer John ordered a high speed connection for his farm and is going to share his connectivity with the other farme
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摘要：Fractions to DecimalsWrite a program that will accept a fraction of the form N/D, where N is the numerator and D is the denominator and print the decimal representation. If the decimal representation has a repeating sequence of digits, indicate the sequence by enclosing it in brackets. For example,
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摘要：The Tamworth TwoBIO '98 - Richard ForsterA 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 empty or they can contain:an obstacle,the cows (wh
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摘要：Bessie Come HomeKolstad & BurchIt's dinner time, and the cows are out in their separate pastures. Farmer John rings the bell so they will start walking to the barn. Your job is to figure out which one cow gets to the barn first (the supplied test data will always have exactly one fastest cow
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摘要：Cow ToursFarmer 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 partitioning Farmer John's farm into m
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摘要：OverfencingKolstad and SchrijversFarmer 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 he created by this overfencing experience is a `perfect'
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摘要：Longest PrefixIOI'96The structure of some biological objects is represented by the sequence of their constituents, where each part is denote by an uppercase letter. Biologists are interested in decomposing a long sequence into shorter ones calledprimitives.We say that a sequence S can be compose
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摘要：Cow PedigreesSilviu Ganceanu -- 2003Farmer John is considering purchasing a new herd of cows. In this new herd, each mother cow gives birth to two children. The relationships among the cows can easily be represented by one or more binary trees with a total of N (3 <= N < 200) nodes. The trees
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摘要：Money SystemsThe cows have not only created their own government but they have chosen to create their own money system. In their own rebellious way, they are curious about values of coinage. Traditionally, coins come in values like 1, 5, 10, 20 or 25, 50, and 100 units, sometimes with a 2 unit coin
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摘要：Controlling CompaniesSome 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 conditions is satisfied:Company A = Company B
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摘要：Preface NumberingA certain book's prefaces are numbered in upper case Roman numerals. Traditional Roman numeral values use a single letter to represent a certain subset of decimal numbers. Here is the standard set: I 1 L 50 M 1000 V 5 C 100 X 10 D 500As ...
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摘要：Party LampsIOI 98To brighten up the gala dinner of the IOI'98 we have a set ofN(10 <= N <= 100) colored lamps numbered from 1 toN.The lamps are connected to four buttons:Button 1: When this button is pressed, all the lamps change their state: those that are ON are turned OFF and those that
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摘要：Subset SumsJRMFor 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 subsets are identical:{3} and {1,2}This counts as a
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摘要：Runaround NumbersRunaround numbers are integers with unique digits, none of which is zero (e.g., 81362) that also have an interesting property, exemplified by this demonstration:If you start at the left digit (8 in our number) and count that number of digits to the right (wrapping back to the first
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摘要：Hamming CodesRob KolstadGiven N, B, and D: Find a set of N codewords (1 <= N <= 64), each of length B bits (1 <= B <= 8), such that each of the codewords is at least Hamming distance of D (1 <= D <= 7) away from each of the other codewords. The Hamming distance between a pair of co
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摘要：Healthy HolsteinsBurch & KolstadFarmer John prides himself on having the healthiest dairy cows in the world. He knows the vitamin content for one scoop of each feed type and the minimum daily vitamin requirement for the cows. Help Farmer John feed his cows so they stay healthy while minimizing t
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摘要：The CastleIOI'94 - Day 1In a stroke of luck almost beyond imagination, Farmer John was sent a ticket to the Irish Sweepstakes (really a lottery) for his birthday. This ticket turned out to have only the winning number for the lottery! Farmer John won a fabulous castle in the Irish countryside.Br
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摘要：Checker ChallengeExamine the 6x6 checkerboard below and note that the six checkers are arranged on the board so that one and only one is placed in each row and each column, and there is never more than one in any diagonal. (Diagonals run from southeast to northwest and southwest to northeast and inc
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