AP Computer Science Exam Question

Consider the following problem:

You are given a string str consisting of lowercase alphabets and an integer k. Your task is to manipulate the string in the following way:

• Remove any contiguous substring of length k from str if the substring contains consecutive characters that are in increasing alphabetical order.

Write a method manipulateString that takes in two parameters: a string str and an integer k, and returns the manipulated string that satisfies the given conditions.

For example, if the input string is "abecdbwgh" and k is 3, the output should be "abwgh".

Signature:

public static String manipulateString(String str, int k)

Input:

• String str represents the input string of lowercase alphabets, where 1 ≤ length of str ≤ 1000.
• Integer k represents the length of contiguous substrings to be checked, where 1 ≤ k ≤ length of str.

Output:

• Return a string representing the manipulated string.

Example

String str = "abecdbwgh";
int k = 3;
System.out.println(manipulateString(str, k));

Output:

abwgh

Explanation

In the given example, the string str is "abecdbwgh" and k is 3.

• We start from the leftmost character of str and consider consecutive substrings of length k.
  • For the first substring "abe", the characters 'a', 'b', 'e' are in increasing alphabetical order, so this substring is removed.
  • The updated str becomes "cdbwgh".
• We move to the next substring "dbw", which does not have consecutive characters in increasing alphabetical order, so it is not removed.
  • The updated str remains "cdbwgh".
• Finally, the last substring "wgh" also does not have consecutive characters in increasing alphabetical order, so it is not removed.
  • The final string after manipulation is "abwgh".

Therefore, the output is "abwgh".