Keyboard Mashings

Of a human being with opinions about things

Hi, I'm David. Sometimes when I have an idea I mash my keyboard and then post the result. Here you can find keyboard mashings about my life, computers, and other stuff.

Archives: 2015



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UVa 10855: Rotated Square

  Tags: uva 2d-array brute-force implementation

Rotated Square is a great problem to tackle if you want practice implementing and manipulating 2D arrays.

Accessing UVa online judge in google chrome: This page has a redirect loop

  Tags: uva

Here’s a problem I had in my early UVa days: I attempted to access the online judge using google chrome, but was met with this:

UVa 10920: Spiral Tap

  Tags: uva implementation

UVa 10920 Spiral Tap gave me quite a bit of grief. What appeared to be a simple simulation pproblem resulted in several TL submissions and many hours of banging my head against my desk before I could find a fast enough solution. Thus my new philsophy: “The more bruises on your head, the more progress you’re making”.

UVa 11581: Grid Successors

  Tags: uva implementation 2d-array

I really liked UVa 11581 Grid Successors because it is a perfect example of the good things that can happen if you don’t let the problem statement scare you.

UVa 10258: Contest Scoreboard

  Tags: uva 2d-array implementation

I did not think that UVa 10258: Contest Scoreboard was a well-written problem. The problem statement did not specify the expected behavior well. I imagine this problem was the subject of many clarification requests when it was used in competition. Then again, I probably just need to practice reading problem statements carefully.

UVa 10264: The Most Potent Corner

  Tags: uva bit-manipulation

I thought UVa 10264: The Most Potent Corner was a fun problem. Short problem description: Given the weights of all of the corners of an n-dimensional unit cube (1 < n < 15), print the maximum sum of the “potencies” of two neighboring corners.

UVa 11933: Splitting Numbers

  Tags: uva implementation

UVa 11933: Splitting Numbers problem summary: Given a number n, print out a and b, where a is the number constructed from every other set bit of n and b is constructed from the other half of the set bits. This problem is simple to implement, but in my case I screwed the implementation up and made things a lot harder for myself.

UVa 11988: Broken Keyboard

  Tags: uva linked-list

UVa 10226: Hardwood Species

  Tags: uva

UVa 10226: Hardwood Species abridged problem statement: Given a list of species of trees, print out each species followed by the percentage of the total tree population it represents. Each species should be on a new line and percentages should be printed to four decimal places.

UVa 11286: Conformity

  Tags: uva

UVa 11926: Multitasking

  Tags: uva implementation

UVa 11136: Hoax or what

  Tags: uva implementation

UVa 11572: Unique Snowflakes

  Tags: uva implementation

UVa 11572: Unique Snowflakes problem description: Given a list of snowflakes (integers), print the length of the longest sublist in which all of the snowflakes are unique.

UVa 11849: CD

  Tags: uva

UVa 1203: Argus

  Tags: uva implementation

UVa 1203: Argus was a sort of poorly written problem, and I thought it was a lot harder than it actually turned out to be.

UVa 978: Lemmings Battle!

  Tags: uva implementation

I solved UVa 978: Lemmings Battle! with a multiset. A multiset has the same underlying implementation as a regular STL set (BST), but it can store multiple copies of the same value, which makes it perfect for modelling these lemmings.

UVa 10895: Matrix Transpose

  Tags: uva

UVa 10954: Add All

  Tags: uva

UVa 11235: Frequent values

  Tags: uva segment-tree

UVa 11235: Frequent values simplified problem statement: You are given an array of integers and a number of queries. Each query is in the form of two positive integers i and j, and your program must print the number of occurances of the most frequently occuring value in the array between indicies i and j, inclusive.

UVa 11991: Easy Problem from Rujia Liu?

  Tags: uva

UVa 11991: Easy Problem from Rujia Liu? simplified problem statement: You are given an array of integers and asked to answer a series of queries. Each query is of the form: “What is the index in the array of the ith occurance of the number j?”

UVa 11995: I Can Guess the Data Structure!

  Tags: uva

UVa 11995: I Can Guess the Data Structure! simplified problem statement: Given a sequence of push/pop operations, state whether the operations are valid for a queue, stack, priority queue, or some combination thereof (including none thereof).

UVa 599: The Forrest for the Trees

  Tags: uva ufds

UVa 10507: Waking up brain

  Tags: uva adjacency-list

UVa 10507: Waking up brain simplified problem statement: There are several areas of the brain, each of which is connected to other areas of the brain. All the regions but 3 are “asleep”, but if a region is connected to 3 awake regions for a year, that region wakes up. Given the connections between various parts of the brain and the 3 regions that are initially awake, determine how long the entire brain takes to wake up.

UVa 11503: Virtual Friends

  Tags: uva ufds

UVa 11503: Virtual Friends simplified problem statement: Several people are friending each other on social media. Every time two people become friends, print out the current size of their social network.

UVa 793: Network Connections

  Tags: uva ufds

UVa 12532: Interval Product

  Tags: uva segment-tree

UVa 12532: Interval Product involves a clever application of segment trees. Abridged problem statement: You are given a list of integers and a number of queries. Each query can either change one integer in the list, or ask for the sign of the product between a range of indicies. Print out a string with the answers to all the queries concatenated together.

UVa 12086: Potentiometers

  Tags: uva fenwick-tree

David Udelson
Cornell University '18
Ithaca, NY
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