![]() ![]() ![]() Given a collection S of subsets of a set X is an exact cover, since the vertex corresponding to each element in X is connected to exactly one selected vertex, as the highlighting makes clear. The N queens problem is a generalized exact cover problem. Following is the link to the 9x9 Diagonal Sudoku puzzles. The exact cover problem can be generalized slightly to involve not only exactly-once constraints but also at-most-once constraints.įinding Pentomino tilings and solving Sudoku are noteworthy examples of exact cover problems. Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns, outlined 3x3 box, and two main marked diagonals. DLX is the name given to Algorithm X when it is implemented efficiently using Donald Knuth's Dancing Links technique on a computer. Knuth's Algorithm X is an algorithm that finds all solutions to an exact cover problem. It is NP-complete even when each subset in S contains exactly three elements this restricted problem is known as exact cover by 3-sets, often abbreviated X3C. The exact cover problem is NP-complete and is one of Karp's 21 NP-complete problems. In computer science, the exact cover problem is a decision problem to determine if an exact cover exists. For example, an exact cover problem is equivalent to an exact hitting set problem, an incidence matrix, or a bipartite graph. But an exact cover problem can be represented by any heterogeneous relation between a set of choices and a set of constraints. ![]() Can you solve these Diagonal Sudokus Explore. The elements of S represent choices and the elements of X represent constraints.Īn exact cover problem involves the relation contains between subsets and elements. Deze is een extreem moeilijke versie van diagonale sudoku. After the Classic Sudoku puzzle, it is the Diagonal Sudoku Puzzle which is the most liked Sudoku variation. While creating Anti Diagonal Sudoku, I realized that creating 6圆 size Sudoku of this type very challenging and interesting. Anti Diagonal Sudoku puzzles can be created both in 9x9 and 6圆 sizes. The exact cover problem to find an exact cover is a kind of constraint satisfaction problem. Anti Diagonal Sudoku is a very interesting Sudoku Variation in which there is a fixed number of digits on the main diagonals which are repeated. In other words, S * is a partition of X consisting of subsets contained in S. One says that each element in X is covered by exactly one subset in S *. In the mathematical field of combinatorics, given a collection S of subsets of a set X, an exact cover is a subcollection S * of S such that each element in X is contained in exactly one subset in S *. Online Diagonal Sudoku - ber eine Million X-Sudoku Puzzles zum Spielen frei verfgbar. Extreme Diagonal Sudoku Puzzles, 4 Puzzles pro Seite. Experten Diagonal Sudoku Puzzles, 4 Puzzles pro Seite. Collection of subsets such that each element of the original set is contained in exactly one subset Schwierige Diagonal Sudoku Puzzles, 4 Puzzles pro Seite. ![]()
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