https://www.hackerrank.com/contests/w35/challenges/3d-surface-area/

3D_Surface_Area.cpp

/*input
3 3
1 3 4
2 2 3
1 2 4
*/

// expected output is 60
 
#include <bits/stdc++.h>

using namespace std;

long surfaceArea(const vector< vector<int> > & a) {
    int rows , cols;
    long count=0;
    rows = a.size();
    cols = a[0].size();

    if ( rows == 0 || cols == 0 ) {
        return 0;
    } else if ( rows == 1 && cols == 1 ) {
        count = 2 + (a[0][0]*4);
    } else if ( rows == 1 ) {
        for (int i = 0; i < cols-1; ++i) {
            count += abs(a[0][i]-a[0][i+1]);
            count += a[0][i]*2;
            // count += 2;
        }
        count += a[0][0];
        count += a[0][cols-1]*3;
        count += 2*cols;

    } else if ( cols == 1 ) {
        for (int i = 0; i < rows-1; ++i) {
            count += abs(a[i][0]-a[i+1][0]);
            count += a[i][0]*2;
            //count += 2;
        }
        count += a[0][0];
        count += a[rows-1][0]*3;
        count += 2*rows;

    } else {
        for (int i = 0; i < rows; ++i) {
            for (int j = 0; j < cols; ++j) {

                if ( i != rows-1 ) {
                    count += abs( a[i][j] - a[i+1][j] );
                }

                if ( j != cols-1 ) {
                    count += abs( a[i][j] - a[i][j+1] );
                }

                if ( i==0 || j==0 || i == rows-1 || j == cols-1 ) {
                    count += a[i][j];
                    if ( i==j || i==cols-1-j || j==rows-1-i ) 
                        count += a[i][j];
                }
            }
        }
        count += 2*rows*cols;
    }

    return count;
}


 
int main()
{
    int H;
    int W;
    cin >> H >> W;
    vector< vector<int> > A(H,vector<int>(W));
    for(int A_i = 0;A_i < H;A_i++){
       for(int A_j = 0;A_j < W;A_j++){
          cin >> A[A_i][A_j];
       }
    }

    long result = surfaceArea(A);

    cout << result << endl;

 
    return 0;
}