vaibhav-35 / sudokusolver

A Very Fast Sudoku Solver made in C++

How to Run ?

• Compiling

  • Standard: g++ solver.cpp -o solver.exe

  • Faster: g++ -O3 solver.cpp -o solver.exe

  • Fastest(not recommended): g++ -Ofast solver.cpp -o solver.exe

• Running

  • Put your sudoku puzzle in puzzle.txt, use numbers to represent given data and 0(Zero) to represent missing data with spaces in between every number.
  • Also put the size of the sudoku on the first line(look at examples in /puzzles)
  • Execute ./solver.exe in the terminal while in the root directory of the project.

How did I achieve this speed ?

• To achieve this performance Donalds Knuths Algorithm X was used.
• The data structure used to implement Algo X is Dancing Links also proposed by Donald Knuth.
• I made a significant improvement in performance building the Toroidal Doubly Linked List to represent the puzzle as an exact cover problem. Time Complexity: O(n^3)
• And then the standard backtracking algorithm as described by Algorithm X.

Tested on a Core i3 7th Gen @ 2.4 Ghz

• 9 X 9 sudoku: 2.029 ms
• 16 X 16: 4.986 ms
• 25 X 25: 15.957 ms

Will be adding a GUI soon