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  1. Prepare
  2. Algorithms
  3. Constructive Algorithms
  4. Flipping the Matrix
  5. Discussions

Flipping the Matrix

  • zgzong1979
     + 1 comment

    Symmetry: We exploit the symmetry of the 2Nx2N matrix to reduce calculations. Maximum value: For each position inside N x N, we find the maximum among the number and its three symmetric counterparts. Summation: The sum of these maximum values gives us the desired result.

        public static int flippingMatrix(List<List<Integer>> matrix) {
        int n = matrix.get(0).size()/2;
        int result = 0; 
        for(int i = 0; i<n; i++) {
            for(int j = 0; j<n; j++){
                result += Math.max(matrix.get(i).get(j), Math.max(matrix.get(2*n-1-i).get(j),
                Math.max(matrix.get(2*n-1-i).get(2*n-1-j), matrix.get(i).get(2*n-1-j))));
            }
        }
        return result;
    }