Most of these answers are horribly inefficient and/or will only give one-word solutions (no spaces). My solution will handle any number of words and is very efficient. What you want is a trie data structure. Here’s a complete Python implementation. You just need a word list saved in a file named words.txt You can try … Read more
#include <stdio.h> int main() { switch (printf(“Hello, world!\n”)) {} } If your friend says “oh, you can’t use switch either,” then: #include <stdio.h> int main(int argc, char *argv[printf(“Hello, world!\n”)]) {}
Okay, here’s my answer using continued fractions alone. First let’s get some terminology here. Let X = p/q be the unknown fraction. Let Q(X,p/q) = sign(X – p/q) be the query function: if it is 0, we’ve guessed the number, and if it’s +/- 1 that tells us the sign of our error. The conventional … Read more
Here is the way my own SuDoKu program does it: Start with a complete, valid board (filled with 81 numbers). Make a list of all 81 cell positions and shuffle it randomly. As long as the list is not empty, take the next position from the list and remove the number from the related cell. … Read more
Update: I liked this topic so much I wrote Programming Puzzles, Chess Positions and Huffman Coding. If you read through this I’ve determined that the only way to store a complete game state is by storing a complete list of moves. Read on for why. So I use a slightly simplified version of the problem … Read more
I looked into this once a long time ago, and you can read my little write-up on it. Here’s the Mathematica source. By using generating functions, you can get a closed-form constant-time solution to the problem. Graham, Knuth, and Patashnik’s Concrete Mathematics is the book for this, and contains a fairly extensive discussion of the … Read more
Ok, so I’m tired as it’s 3AM here, but I have a first try inplace with exactly 2 passes on each number in the matrix, so in O(NxN) and it is linear in the size of the matrix. I use 1rst column and first row as markers to know where are rows/cols with only 1’s. … Read more
SELECT MAX( col ) FROM table WHERE col < ( SELECT MAX( col ) FROM table )
My answer works like the others here, but I’ll post it because it looks a bit faster than the other Python solutions, from setting up the dictionary faster. (I checked this against John Fouhy’s solution.) After setup, the time to solve is down in the noise. grid = “fxie amlo ewbx astu”.split() nrows, ncols = … Read more
This is equivalent to Adam Rosenfield’s solution, but may be a bit more clear for some readers. It assumes rand5() is a function that returns a statistically random integer in the range 1 through 5 inclusive. int rand7() { int vals[5][5] = { { 1, 2, 3, 4, 5 }, { 6, 7, 1, 2, … Read more