Answer: Samsara SWE Interview Question 2024 May | Matrix | on-campus

Solution 1: Valid Sudoku — Hash Set String Signatures Approach We can solve this problem in a single pass of the 9 x 9 grid. To validate rows, columns, and 3 x 3 boxes simultaneously, we can use a **HashSet** storing unique string "signatures": Iterate through all 81 cells in the grid. If the cell contains '.', skip it. If the cell contains a digit val at coordinates (r, c): Represent row validation as: "val in row r". Represent column ...