Project euler memo #43

Problem 89: Problem of Roman numerals. Very easy and fun. I remember that my math teacher of my junior high school taught us how to write numbers in Roman numerals. I would probably see some in Rome when I get there next month.

Project euler memo #42

Problem 86: One more problem on Pythagorean numbers. The idea is simple but the programming is a bit tricky. This is my 110th problem.

Project euler memo #41

Problem 94: Almost equilateral triangle problem. Generated Pythagorean numbers and counted the perimeters of the triangles. Straightforward and simple solution.

Project euler memo #40

Problem 108: Interesting problem. I tried with brute force which is time consuming, and while I was watching the increasing numbers I noticed that it can be solved in an easy way.

I have some problems that I got right answers but take time more than one minute. I am re-writing my original python codes to C codes ant it works fine. These are problems such as 14, 34 and 92.

Project euler memo #39

Problem 172: Simple combinatorial problem. But I had an English problem: if x is not "more than three", I thought x could not be three. Now I know I was wrong.

Project euler memo #38

Problem 77: A partition problem. It looked like a hard and a mathematical problem but in fact a straight forward way works.

Project euler memo #37

Problem 113: Bouncy numbers problem. I stared by counting the increasing and decreasing numbers by pencil, and reached a formula. The meaning of the formula is explained in the 113 forum.

Project euler memo #36

104th problem.
Problem 91: Find triangles with a right angle. There are much more triangles than I expected.

Project euler memo #35

Problem 187: Semiprimes. My original version was so stupid and took more than three minutes. I learned in the forum how stupid I was and I wrote a nicer one. It takes 30 seconds.

That's my 103th problem.

Project euler memo #34

My 102th problem.

Problem 173: Counting square laminae. Problem 174 is a related problem. This is not very hard.