A cool algorithm to check a Sudoku field?

Question

Does anyone know a simple algorithm to check if a Sudoku-Configuration is valid? The simplest algorithm I came up with is (for a board of size n) in Pseudocode

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Answer 1

First, you would need to make a boolean, "correct". Then, make a for loop, as previously stated. The code for the loop and everything afterwards (in java) is as stated, where field is a 2D array with equal sides, col is another one with the same dimensions, and l is a 1D one:

for(int i=0; i9||field[i][j]<1){
            checking=false;
            break;
        }
        else{
            col[field[i].length()-j][i]=field[i][j];
        }
    }
}

I don't know the exact algorithim to check the 3x3 boxes, but you should check all the rows in field and col with "/*array name goes here*/[i].contains(1)&&/*array name goes here*/[i].contains(2)" (continues until you reach the length of a row) inside another for loop.