At the beginning of spring all the sheep move to the higher pastures in the mountains. If there are thousands of them, it is well worthwhile gathering them together in one place. But sheep don’t like to leave their grass-lands. Help the shepherd and build him a fence which would surround all the sheep. The fence should have the smallest possible length! Assume that sheep are negligibly small and that they are not moving. Sometimes a few sheep are standing in the same place. If there is only one sheep, it is probably dying, so no fence is needed at all … Input t [the number of tests <= 100] [empty line] n [the number of sheep <= 100000] x1 y1 [coordinates of the first sheep] … xn yn [integer coordinates from -10000 to 10000] [empty line] [other lists of sheep] Text grouped in [ ] does not appear in the input file.… Read more →

# EppsNet Archive: Competitive Programming

## Competitive Programming: POJ 2185 – Milking Grid

Description Every morning when they are milked, the Farmer John’s cows form a rectangular grid that is R (1 <= R <= 10,000) rows by C (1 <= C <= 75) columns. As we all know, Farmer John is quite the expert on cow behavior, and is currently writing a book about feeding behavior in cows. He notices that if each cow is labeled with an uppercase letter indicating its breed, the two-dimensional pattern formed by his cows during milking sometimes seems to be made from smaller repeating rectangular patterns. Help FJ find the rectangular unit of smallest area that can be repetitively tiled to make up the entire milking grid. Note that the dimensions of the small rectangular unit do not necessarily need to divide evenly the dimensions of the entire milking grid, as indicated in the sample input below. Input Line 1: Two space-separated integers: R and C… Read more →

## Competitive Programming: POJ 1147 – Binary Codes

Description Consider a binary string (b1…bN) with N binary digits. Given such a string, the matrix of Figure 1 is formed from the rotated versions of the string. b1 b2 … bN-1 bN b2 b3 … bN b1 … bN-1 bN … bN-3 bN-2 bN b1 … bN-2 bN-1 Figure 1. The rotated matrix Then rows of the matrix are sorted in alphabetical order, where ‘0’ is before ‘1’. You are to write a program which, given the last column of the sorted matrix, finds the first row of the sorted matrix. As an example, consider the string (00110). The sorted matrix is 0 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 0 0 1 1 1 0 0 0 and the corresponding last column is (1 0 0 1 0). Given this last column your program should determine the first row, which is… Read more →

## Competitive Programming: POJ 1961 – Period

Description For each prefix of a given string S with N characters (each character has an ASCII code between 97 and 126, inclusive), we want to know whether the prefix is a periodic string. That is, for each i (2 <= i <= N) we want to know the largest K > 1 (if there is one) such that the prefix of S with length i can be written as AK, that is A concatenated K times, for some string A. Of course, we also want to know the period K. Input The input consists of several test cases. Each test case consists of two lines. The first one contains N (2 <= N <= 1,000,000) – the size of the string S. The second line contains the string S. The input file ends with a line, having the number zero on it. Output For each test case, output “Test… Read more →

## Competitive Programming: POJ 2074 – Line of Sight

Description An architect is very proud of his new home and wants to be sure it can be seen by people passing by his property line along the street. The property contains various trees, shrubs, hedges, and other obstructions that may block the view. For the purpose of this problem, model the house, property line, and obstructions as straight lines parallel to the x axis: Input Because each object is a line, it is represented in the input file with a left and right x coordinate followed by a single y coordinate: <x1> <x2> <y> where x1, x2, and y are non-negative real numbers, x1 < x2 . An input file can describe the architecture and landscape of multiple houses. For each house, the first line will have the coordinates of the house. The second line will contain the coordinates of the property line. The third line will have a… Read more →

## Competitive Programming: POJ 2318 – TOYS

Description Calculate the number of toys that land in each bin of a partitioned toy box. Mom and dad have a problem – their child John never puts his toys away when he is finished playing with them. They gave John a rectangular box to put his toys in, but John is rebellious and obeys his parents by simply throwing his toys into the box. All the toys get mixed up, and it is impossible for John to find his favorite toys. John’s parents came up with the following idea. They put cardboard partitions into the box. Even if John keeps throwing his toys into the box, at least toys that get thrown into different bins stay separated. The following diagram shows a top view of an example toy box. For this problem, you are asked to determine how many toys fall into each partition as John throws them into… Read more →

## Competitive Programming: POJ 1905 – Expanding Rods

Description When a thin rod of length L is heated n degrees, it expands to a new length L’=(1+n*C)*L, where C is the coefficient of heat expansion. When a thin rod is mounted on two solid walls and then heated, it expands and takes the shape of a circular segment, the original rod being the chord of the segment. Your task is to compute the distance by which the center of the rod is displaced. Input The input contains multiple lines. Each line of input contains three non-negative numbers: the initial lenth of the rod in millimeters, the temperature change in degrees and the coefficient of heat expansion of the material. Input data guarantee that no rod expands by more than one half of its original length. The last line of input contains three negative numbers and it should not be processed. Output For each line of input, output one… Read more →

## Competitive Programming: CodeSignal – footballGroupStatictics (A World Cup SQL Challenge)

Description You are creating a website that will help you and your friends keep track of the results of soccer games from all around the world. You store all results of one group in a table, results. You want to sort the teams in a complex way – first by points, then by total goal differences, and then by total goals. If all of these parameters are equal, sort the teams alphabetically. The results table contains the following columns: first_team – the name of the first team; second_team – the name of the second team; first_team_score – the number of goals scored by the first team; second_team_score – the number of goals scored by the second team. Here the primary key is the pair (first_team, second_team). Return the list of team names sorted in the way described above. Note: see three points for a win to understand how points are… Read more →

## Competitive Programming: CodeSignal – canScore (A World Cup Challenge)

Description Your friend is a soccer fan and you were watching some World Cup matches with him. You liked this game, but the rules are very complicated for you, so you decided just to try to guess whether the given attack will end with a goal or not. In the beginning, the ball is in the attacking team’s goalkeeper’s hands. On the attacking team, there’s a very talented goalscorer, who is waiting for his chance at the other end of the field. His teammates want to give him the ball so he can score. They can move the ball by passing it one to another along a straight line, but the defender can steal the pass if he is closer than d to the ball at any point throughout the pass. Now you want to know if the attacking team can score or not. Formally, you are given the coordinates… Read more →

## Competitive Programming: POJ 3281- Dining

Description Cows are such finicky eaters. Each cow has a preference for certain foods and drinks, and she will consume no others. Farmer John has cooked fabulous meals for his cows, but he forgot to check his menu against their preferences. Although he might not be able to stuff everybody, he wants to give a complete meal of both food and drink to as many cows as possible. Farmer John has cooked F (1 <= F <= 100) types of foods and prepared D (1 <= D <= 100) types of drinks. Each of his N (1 <= N <= 100) cows has decided whether she is willing to eat a particular food or drink a particular drink. Farmer John must assign a food type and a drink type to each cow to maximize the number of cows who get both. Each dish or drink can only be consumed by… Read more →

## Competitive Programming: POJ 2455 – Secret Milking Machine

Description Farmer John is constructing a new milking machine and wishes to keep it secret as long as possible. He has hidden in it deep within his farm and needs to be able to get to the machine without being detected. He must make a total of T (1 <= T <= 200) trips to the machine during its construction. He has a secret tunnel that he uses only for the return trips. The farm comprises N (2 <= N <= 200) landmarks (numbered 1..N) connected by P (1 <= P <= 40,000) bidirectional trails (numbered 1..P) and with a positive length that does not exceed 1,000,000. Multiple trails might join a pair of landmarks. To minimize his chances of detection, FJ knows he cannot use any trail on the farm more than once and that he should try to use the shortest trails. Help FJ get from the barn… Read more →

## Competitive Programming: POJ 2195 – Going Home

Description On a grid map there are n little men and n houses. In each unit time, every little man can move one unit step, either horizontally, or vertically, to an adjacent point. For each little man, you need to pay a $1 travel fee for every step he moves, until he enters a house. The task is complicated with the restriction that each house can accommodate only one little man. Your task is to compute the minimum amount of money you need to pay in order to send these n little men into those n different houses. The input is a map of the scenario, a ‘.’ means an empty space, an ‘H’ represents a house on that point, and am ‘m’ indicates there is a little man on that point. You can think of each point on the grid map as a quite large square, so it can… Read more →

## Competitive Programming: POJ 3169 – Layout

Description Like everyone else, cows like to stand close to their friends when queuing for feed. FJ has N (2 <= N <= 1,000) cows numbered 1..N standing along a straight line waiting for feed. The cows are standing in the same order as they are numbered, and since they can be rather pushy, it is possible that two or more cows can line up at exactly the same location (that is, if we think of each cow as being located at some coordinate on a number line, then it is possible for two or more cows to share the same coordinate). Some cows like each other and want to be within a certain distance of each other in line. Some really dislike each other and want to be separated by at least a certain distance. A list of ML (1 <= ML <= 10,000) constraints describes which cows like… Read more →

## Competitive Programming: POJ 1125 – Stockbroker Grapevine

Description Stockbrokers are known to overreact to rumors. You have been contracted to develop a method of spreading disinformation amongst the stockbrokers to give your employer the tactical edge in the stock market. For maximum effect, you have to spread the rumors in the fastest possible way. Unfortunately for you, stockbrokers only trust information coming from their “Trusted sources” This means you have to take into account the structure of their contacts when starting a rumor. It takes a certain amount of time for a specific stockbroker to pass the rumor on to each of his colleagues. Your task will be to write a program that tells you which stockbroker to choose as your starting point for the rumor, as well as the time it will take for the rumor to spread throughout the stockbroker community. This duration is measured as the time needed for the last person to receive… Read more →

## Competitive Programming: POJ 2488 – A Knight’s Journey

Description Background The knight is getting bored of seeing the same black and white squares again and again and has decided to make a journey around the world. Whenever a knight moves, it is two squares in one direction and one square perpendicular to this. The world of a knight is the chessboard he is living on. Our knight lives on a chessboard that has a smaller area than a regular 8 * 8 board, but it is still rectangular. Can you help this adventurous knight to make travel plans? Problem Find a path such that the knight visits every square once. The knight can start and end on any square of the board. Input The input begins with a positive integer n in the first line. The following lines contain n test cases. Each test case consists of a single line with two positive integers p and q, such… Read more →

## Competitive Programming: POJ 1159 – Palindrome

Description A palindrome is a symmetrical string, that is, a string read identically from left to right as well as from right to left. You are to write a program which, given a string, determines the minimal number of characters to be inserted into the string in order to obtain a palindrome. As an example, by inserting 2 characters, the string “Ab3bd” can be transformed into a palindrome (“dAb3bAd” or “Adb3bdA”). However, inserting fewer than 2 characters does not produce a palindrome. Input Your program is to read from standard input. The first line contains one integer: the length of the input string N, 3 <= N <= 5000. The second line contains one string with length N. The string is formed from uppercase letters from ‘A’ to ‘Z’, lowercase letters from ‘a’ to ‘z’ and digits from ‘0’ to ‘9’. Uppercase and lowercase letters are to be considered distinct.… Read more →

## Competitive Programming: POJ 2663 – Tri Tiling

Description In how many ways can you tile a 3xn rectangle with 2×1 dominoes? Here is a sample tiling of a 3×12 rectangle. Input Input consists of several test cases followed by a line containing -1. Each test case is a line containing an integer 0 <= n <= 30. Output For each test case, output one integer number giving the number of possible tilings. Sample Input 2 8 12 -1 Sample Output 3 153 2131 Link to problem Solution below . . . Read more →

## Competitive Programming: POJ 1426 – Find The Multiple

Description Given a positive integer n, write a program to find out a nonzero multiple m of n whose decimal representation contains only the digits 0 and 1. You may assume that n is not greater than 200 and there is a corresponding m containing no more than 100 decimal digits. Input The input file may contain multiple test cases. Each line contains a value of n (1 <= n <= 200). A line containing a zero terminates the input. Output For each value of n in the input print a line containing the corresponding value of m. The decimal representation of m must not contain more than 100 digits. If there are multiple solutions for a given value of n, any one of them is acceptable. Sample Input 2 6 19 0 Sample Output 10 100100100100100100 111111111111111111 Link to problem Solution below . . . Read more →

## Competitive Programming: POJ 2084 – Game of Connections

Description This is a small but ancient game. You are supposed to write down the numbers 1, 2, 3, . . . , 2n – 1, 2n consecutively in clockwise order on the ground to form a circle, and then, to draw some straight line segments to connect them into number pairs. Every number must be connected to exactly one another. And, no two segments are allowed to intersect. It’s still a simple game, isn’t it? But after you’ve written down the 2n numbers, can you tell me in how many different ways can you connect the numbers into pairs? Life is harder, right? Input Each line of the input file will be a single positive number n, except the last line, which is a number -1. You may assume that 1 < = n Read more →

## Competitive Programming: USACO Big Barn

Farmer John wants to place a big square barn on his square farm. He hates to cut down trees on his farm and wants to find a location for his barn that enables him to build it only on land that is already clear of trees. For our purposes, his land is divided into N x N parcels. The input contains a list of parcels that contain trees. Your job is to determine and report the largest possible square barn that can be placed on his land without having to clear away trees. The barn sides must be parallel to the horizontal or vertical axis. EXAMPLE Consider the following grid of Farmer John’s land where ‘.’ represents a parcel with no trees and ‘#’ represents a parcel with trees: 1 2 3 4 5 6 7 8 1 . . . . . . . . 2 . # .… Read more →