Find the "balance number" in a matrix | Hello World

Find the “balance number” in a matrix | Hello World
The balance number in a matrix is defined as the number whose sum of the elements in rows above it equals the sum of elements in rows below, and same for the columns. For the rows, we make two arrays, one stores the sum of all elements of rows up to the current row index, the other stores sum of all elements from the current row index to the end. Same for the columns, Then we can simply scan all the elements and look into those arrays to find out if it is balanced or not.

    public static ArrayList<String> balanceNum(int [][] matrix) {

        int noCol = matrix[0].length;

        int noRow = matrix.length;

        int [] sumRow = new int [noRow];

        int [] sumCol = new int [noCol];

        for(int r = 0; r < noRow; r++) {

            for (int c = 0; c < noCol; c++) {

                sumRow[r] += matrix[r][c];

            }

        }

        for (int c = 0; c < noCol; c++) {

            for (int r = 0; r < noRow; r++) {

                sumCol[c] += matrix[r][c];

            }

        }

         

        int [] dpRabove = new int [noRow];

        dpRabove[0] = sumRow[0];

        for (int i = 1; i < noRow; i++) {

            dpRabove[i] = dpRabove[i-1] + sumRow[i];

        }

         

        int [] dpRbelow = new int [noRow];

        dpRbelow[noRow-1] = sumRow[noRow-1];

        for (int i = noRow - 2; i >= 0; i--) {

            dpRbelow[i] = dpRbelow[i+1] + sumRow[i];

        }

         

        int [] dpCabove = new int [noCol];

        dpCabove[0] = sumCol[0];

        for (int i = 1; i < noCol; i++) {

            dpCabove[i] = dpCabove[i-1] + sumCol[i];

        }

         

        int [] dpCbelow = new int [noCol];

        dpCbelow[noCol - 1] = sumCol[noCol-1];

        for (int i = noCol - 2; i >= 0; i--) {

            dpCbelow[i] = dpCbelow[i+1] + sumCol[i];

        }

         

        ArrayList<String> res = new ArrayList<String>();

        for (int r = 1; r < noRow-1; r++) {

            for (int c = 1; c < noCol-1; c++) {

                if (dpCabove[c-1] == dpCbelow[c+1] && dpRabove[r-1] == dpRbelow[r+1]) {

                    String tmp = new String("" + (char)(r + '0') + "," + (char)(c + '0'));

                    res.add(tmp);

                }

            }

        }

        return res;

    }

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