Backtracking Backtracking is a way to speed up the search process by removing candidates when they can't be the solution of a problem. https://en.wikipedia.org/wiki/Backtracking https://en.wikipedia.org/wiki/Decision_tree_pruning https://medium.com/@priyankmistry1999/backtracking-sudoku-6e4439e4825c https://www.geeksforgeeks.org/sudoku-backtracking-7/
