Least Error Cartesian Meshing

This is actually the Project Euler problem of last week – I know it’s not good to post the answer of new problems here, but this is indeed a very intriguing problem. In short, the problem is as follows: Given a unit circle within radius of 1, we try to represent it by non-uniform mesh. N lines are inserted into the square [-1, 1] x [-1, 1]. Cells are colored red if they overlap with the unit circle, black otherwise. Find the way to make the red area minimum. Here is my solution on N = 16. Continue reading “Least Error Cartesian Meshing”

Sudoku Solution – Project Euler #96

This is a Python solution for Project Euler #96, to find the solution for sudokus.

The speed is modest (0.750s with pypy on Windows 7 @ i5 2.60GHz), but the code is relatively short and hopefully the idea is clear. Enjoy.
1. Find candidates for all items. If only one exists for a blank, fill it in.
2. Note down the blank with least but more than one candidates.
3. Copy the matrix and trial the candidates recursively until all blanks are filled.
Continue reading “Sudoku Solution – Project Euler #96”