Nedbank Mock: Minimum Scheduling Operations (Q72)

[sudosf]

Problem

Given a string of only 'a', 'b', 'c' characters, find the minimum number of character insertions to make it a concatenation of one or more "abc" repetitions.

Source

Nedbank VAS HackerRank Assessment - Q72
Tags: Easy, Strings

Constraints

• 1 <= length of s <= 10^5
• s consists only of 'a', 'b', 'c'

Examples

s="abb" -> 3  (transform to "abcabc")
s="aa"  -> 4  (transform to "abcabc")
s="ac"  -> 1  (insert 'b' to get "abc")

Approach Hints

• Each character in s maps to an expected position within a repeating cycle of 3 ('a'=0, 'b'=1, 'c'=2)
• Walk through s tracking which position in the cycle you expect next
• What happens when the current char is ahead of or behind the expected position?

Notes

Language: Java