Valid Sudoku

Problem: Valid Sudoku You are given a 9 x 9 Sudoku grid. Decide whether the entries currently placed on it are valid. Check only cells that already contain a digit, using these requirements: No row may repeat any digit from 1-9. No column may contain the same digit from 1-9 more than once. Within each of the nine 3 x 3 regions, every digit from 1-9 may occur at most once. A '.' marks a blank square, which is not considered during validation. Notes: A board can pass…