Sudoku puzzleAlgebra Level 1
What's the sum of all the numbers filled into a sudoku(数独）puzzle?
NOTE: A sudoku puzzle is a 9x9 grid.
Each line and column needs to be filled with number 1 through 9 without repetition.
There are 9 3x3 squares in the 9x9 grid, each 3x3 square needs to be filled with numbers 1 through 9 without repetition.