Blogs

Euler Problem 102 asks: 'Three distinct points are plotted at random on a Cartesian plane, for which '-1000 LTE x, y LTE 1000, such that a triangle is formed. ' 'Consider the following two triangles: ' 'A(-340,495), B(-153,-910), C(835,-947) ' 'X(-175,41), Y(-421,-714), Z(574,-645) ' 'It can be verified that triangle ABC contains the origin, whereas 'triangle XYZ does not. ' 'Using triangles.txt (right click and 'Save [...] Read More...

A common misconception some (many?) have about recursive solutions is that they are not fast. There are many reasons to use recursion, both in code and in data, mainly that solutions based on recursion are easy to implement, understand, and maintain. For an introduction see Recursion (http://www.tushar-mehta.com/publish_train/book_vba/07_recursion.htm). What is interesting is that recursive solutions [...] Read More...

Two problems so far, Eulers 22 and 29, have required sorts, at least for my implementations. Euler 22 sorts over 5000 name strings, and Euler 29 sorts nearly 10,000 numerics. In both cases I used a bubble sort. Bubble sorts get their name from the image of the greater-valued item "bubbling up" [...] Read More...

For 2009, I resolve to stop keeping detailed track of my time at work. It started as a small experiment to see where I was spending my time. There weren’t any real surprises in the data. I guess one surprise was how easy it was to use the tool I built to [...] Read More...

Problem 55 asks: 'If we take 47, reverse and add, 47 + 74 = 121, which is palindromic. ' 'Not all numbers produce palindromes so quickly. For example, ' '349 + 943 = 1292, '1292 + 2921 = 4213 '4213 + 3124 = 7337 ' 'That is, 349 took three iterations to arrive at a palindrome. ' 'Although no one has proved it yet, it is [...] Read More...

I don’t use user defined functions in add-ins all that often, but I happen to have a particular add-in with one UDF. And I happened to have recently moved that add-in. And all my links happen to be broken. Fortunately, Jan Karel has an exhaustive write-up on how to fix and prevent this problem. [...] Read More...

Long time reader Michael Tollefson has been messing around with Project Euler. He has graciously offered to post some of his exploits here. Expect some posts from Michael soon. Read More...

It’s college football bowl season once again. I have a spreadsheet I use to help me identify winners and losers (for entertainment purposes only). The four yardage columns are yards per game for rushing offense, rushing defense, passing offense, and passing defense, respectively. I’m trying to identify teams that have better defenses (because defense [...] Read More...