Task

Find and display the sum of elements that are below the main diagonal of a matrix.

The matrix should be a square matrix.



 ───   Matrix to be used:   ───


     [[1,3,7,8,10],
      [2,4,16,14,4],
      [3,1,9,18,11],
      [12,14,17,18,20],
      [7,1,3,9,5]] 



type SquareMatrix[T: SomeNumber; N: static Positive] = array[N, array[N, T]]
 
func sumBelowDiagonal[T, N](m: SquareMatrix[T, N]): T =
  for i in 1..<N:
    for j in 0..<i:
      result += m[i][j]
 
const M = [[ 1,  3,  7,  8, 10],
           [ 2,  4, 16, 14,  4],
           [ 3,  1,  9, 18, 11],
           [12, 14, 17, 18, 20],
           [ 7,  1,  3,  9,  5]]
 
echo sumBelowDiagonal(M)