Implement the sudokuValidPlacementCount method that counts how many filled Sudoku cells are validly placed.
The input contains a Sudoku-style board and its size n.
Your task is to count how many filled positions are valid according to the placement rules. A filled value is valid when the same value does not appear again in its row, column, or related box area.
Empty cells are represented by . and are not treated as fixed duplicate values. The final count tells how many board positions pass the validity check.
Example 1
[[5,3,.],[6,.,.],[.,9,8]]37Example 2
[[1,2,3],[4,5,6],[7,8,9]]39Example 3
[[1,1,3],[4,5,6],[7,8,9]]37Check every filled cell against the rest of the board.
For each non-empty cell, compare its value with other cells in the same row and column. In a normal Sudoku board, you should also compare it with cells in the same sub-box. If another cell with the same value is found in any restricted area, that placement is not valid.
Count only the positions that pass the duplicate check.
Pseudocode:
function sudokuValidPlacementCount(board, n):
count = 0
for row from 0 to n - 1:
for col from 0 to n - 1:
if board[row][col] == '.':
continue
if isValidPlacement(row, col, board[row][col]):
count++
return count
function isValidPlacement(row, col, value):
for each other column in the same row:
if board[row][otherColumn] == value:
return false
for each other row in the same column:
if board[otherRow][col] == value:
return false
check the related box area if required
return true