PLEASE TYPE ONLY*** Exercise 5.3.1: Counting passwords without repeating characters. Consider the following definitions for sets of characters: Digits = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 } Letters = { a,...

PLEASE TYPE ONLY***

Exercise 5.3.1: Counting passwords without repeating characters.

Consider the following definitions for sets of characters:

• Digits = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }


• Letters = { a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z }


• Special characters = { *, &, $, # }

Compute the number of passwords that satisfy the given constraints.

(a)

Strings of length 6. Characters can be special characters, digits, or letters, with no repeated characters.

(b)

Strings of length 6. Characters can be special characters, digits, or letters, with no repeated characters. The first character can not be a special character.