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  1. Prepare
  2. Algorithms
  3. Implementation
  4. 3D Surface Area
  5. Discussions

3D Surface Area

  • captaingabi
     + 0 comments

    Algo:

    • Take 2 times H*W, this is the top and bottom facing faces
    • Calculate left-right facing faces in a given row:
      • take first element
      • add absolute value of difference between each element
      • add last element
    • Calculate front-back facing faces in a given coloumn the same way

    C++ with going through the matrix only once:

    int surfaceArea(vector<vector<int>> A) {
    int area = 2 * A.size() * A[0].size();
    
    for(int i = 0; i < A.size(); i++){
        for(int j = 0; j < A[i].size(); j++){

            if(j == 0) area += A[i][j];
            if(j == A[i].size() - 1) area += A[i][j];
            if(j > 0 and j < A[i].size()) area += abs(A[i][j] - A[i][j-1]);

            if(i == 0) area += A[i][j];
            if(i == A.size() - 1) area += A[i][j];
            if(i > 0 and i < A.size()) area += abs(A[i][j] - A[i-1][j]);
        }
    }

    return area;
}