An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. For example, 371 is an Armstrong number, since 33 + 73 + 13 = 371. Write a method called isArmstrongNum to determine if a given number is an Armstrong number. Write a program that generates 100 three-digit random numbers and calls isArmstrongNum method to find all Armstrong numbers among these 100 random numbers.