A letter pair is two of the same character appearing next to each other in a string. E.g. in the string "terrifically" there are 2 letter pairs "rr" and "ll".
Write a program that reads a lowercase string as input, counts and prints out the number of letter pairs in a word.
The input string will have length 2-64 and be made of only lowercase alphabetical characters (a-z). There will be no spaces or punctuation marks.
Two letter pairs of the same character, e.g. the two pairs of “ee” found in “beekeeper,” both count as separate letter pairs.
No letters will appear consecutively more than twice (e.g. "aaa" will not be an input).
Input:
$ dcc letter_pairs.c -o letter_pairs
$ ./letter_pairs
beekeeper
Output:
2
Explanation: The double letter pair “ee” occurs twice in this word.
Input:
$ dcc letter_pairs.c -o letter_pairs
$ ./letter_pairs
balloon
Output:
2
Explanation: The double letter pairs “ll” and “oo” each appear once in this word, so there are two double letter pairs.
Input:
$ dcc letter_pairs.c -o letter_pairs
$ ./letter_pairs
distinction
Output:
0
Explanation: There are no double letter pairs in this word - although some letters appear twice in the word, they do not appear consecutively, so they do not count as double letters.
When you think your program is working, you can use CSE autotest to test your solution.
$ 1511 csesoc-autotest letter_pairs
You can view the solution code to this problem here.