message: Update n-th-tribonacci-number.py
diff: @@ -25,10 +25,10 @@ class Solution(object):
  return [[sum(a*b for a, b in itertools.izip(row, col)) \
  for col in ZB] for row in A]
  - T = [[1, 1, 1],
  - [1, 0, 0],
  - [0, 1, 0]]
  - return matrix_expo(T, n)[1][0]
  + T = [[1, 1, 0],
  + [1, 0, 1],
  + [1, 0, 0]]
  + return matrix_mult([[1, 0, 0]], matrix_expo(T, n))[0][1] # [a1, a0, a(-1)] * T^n
  # Time: O(n)
  