puzzle

This question already has an answer here: How to generate Sudoku boards with unique solutions 9 answers How many possible unique ways are there to generate a Sudoku Puzzle?? I can think of only two possible ways 1) Take a solved Sudoku puzzle and shuffle the rows and columns 2) Generate a random number and check if it violates any Sudoku constraints, repeat untill number does not violate any Sudoku constraint for every square(theoretically possible but normally it leads to deadlocking ) Are there any other ways? Here is a 20-page PDF, titled "Sudoku Puzzles Generating: from Easy to Evil", that

How can I find the factorial of a number (from 1 to 10) in C, without using: loop statements like for, while, and do while; conditional operators like if and case; and arithmetic operators like + , − , * , % , /, ++, −−? FYI: I found this question in C aptitude. Brian R. Bondy Since it is only 1 to 10, simply precompute it and store it in a simple int array of size 11. For the first element in the array put 1. It is not a valid input range for your problem but might as well be correct. We need to store 11 elements instead of the 10 we need because otherwise we'd need to use operation "-" to

Can someone explain to me why this code prints 14? I was just asked by another student and couldn't figure it out. int i = 5; i = ++i + ++i; cout<<i; The order of side effects is undefined in C++. Additionally, modifying a variable twice in a single expression has no defined behavior (See the C++ standard , §5.0.4, physical page 87 / logical page 73). Solution: Don't use side effects in complex expression, don't use more than one in simple ones. And it does not hurt to enable all the warnings the compiler can give you: Adding -Wall (gcc) or /Wall /W4 (Visual C++) to the command line yields a

A friend gave me a puzzle that he says can be solved in better than O(n^3) time. Given a set of n jobs that each have a set start time and end time (overlaps are very possible), find the smallest subset that for every job either includes that job or includes a job that has overlap with that job. I'm pretty sure that the optimal solution is to pick the job with the most unmarked overlap, add it to the solution set, then mark it, and its overlap. And repeat until all jobs are marked. Figuring out which job has the most unmarked overlappers is a simple adjacency matrix (O(n^2)), and this has to