Merge Close Characters

Description

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Solutions

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Medium

You are given a string s consisting of lowercase English letters and an integer k.

Two equal characters in the current string s are considered close if the distance between their indices is at most k.

When two characters are close, the right one merges into the left. Merges happen one at a time, and after each merge, the string updates until no more merges are possible.

Return the resulting string after performing all possible merges.

Note: If multiple merges are possible, always merge the pair with the smallest left index. If multiple pairs share the smallest left index, choose the pair with the smallest right index.

Example 1:

Input: s = "abca", k = 3

Output: "abc"

Explanation:

Characters 'a' at indices i = 0 and i = 3 are close as 3 - 0 = 3 <= k.
Merge them into the left 'a' and s = "abc".
No other equal characters are close, so no further merges occur.

Example 2:

Input: s = "aabca", k = 2

Output: "abca"

Explanation:

Characters 'a' at indices i = 0 and i = 1 are close as 1 - 0 = 1 <= k.
Merge them into the left 'a' and s = "abca".
Now the remaining 'a' characters at indices i = 0 and i = 3 are not close as k < 3, so no further merges occur.

Example 3:

Input: s = "yybyzybz", k = 2

Output: "ybzybz"

Explanation:

Characters 'y' at indices i = 0 and i = 1 are close as 1 - 0 = 1 <= k.
Merge them into the left 'y' and s = "ybyzybz".
Now the characters 'y' at indices i = 0 and i = 2 are close as 2 - 0 = 2 <= k.
Merge them into the left 'y' and s = "ybzybz".
No other equal characters are close, so no further merges occur.

Constraints:

1 <= s.length <= 100
1 <= k <= s.length
s consists of lowercase English letters.

Code

Testcase

Test Result