puzzle

How do you generate a Sudoku board with a unique solution? What I thought was to initialize a random board and then remove some numbers. But my question is how do I maintain the uniqueness of a solution? TMS Easy: Find all solutions with an efficient backtracking algorithm. If there is just one solution, you are done. Otherwise if you have more than one solution, find a position at which most of the solutions differ. Add the number at this position. Go to 1. I doubt you can find a solution that would be much faster than this. Here is the way my own SuDoKu program does it: Start with a complete

What would be the best strategy to generate anagrams. An anagram is a type of word play, the result of rearranging the letters of a word or phrase to produce a new word or phrase, using all the original letters exactly once; ex. Eleven plus two is anagram of Twelve plus one A decimal point is anagram of I'm a dot in place Astronomers is anagram of Moon starers At first it looks straightforwardly simple, just to jumble the letters and generate all possible combinations. But what would be the efficient approach to generate only the words in dictionary. I came across this page, Solving anagrams

This question already has an answer here: How to find the only number in an array that doesn't occur twice [duplicate] 5 answers What would be the best algorithm for finding a number that occurs only once in a list which has all other numbers occurring exactly twice. So, in the list of integers (lets take it as an array) each integer repeats exactly twice, except one. To find that one, what is the best algorithm. The fastest (O(n)) and most memory efficient (O(1)) way is with the XOR operation. In C: int arr[] = {3, 2, 5, 2, 1, 5, 3}; int num = 0, i; for (i=0; i < 7; i++) num ^= arr[i]; printf