How do you solve Minimum Operations to Sort a String on LeetCode?

Minimum Operations to Sort a String (LeetCode #3863) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(1) space complexity. Key insight: Identifying the positions of min and max characters is crucial.

What is the time complexity of Minimum Operations to Sort a String?

The optimal solution for Minimum Operations to Sort a String runs in O(n) time and uses O(1) space. This complexity arises from scanning the string to find min and max characters, which is O(n).

What is the brute force solution for Minimum Operations to Sort a String?

The brute force approach for Minimum Operations to Sort a String is Brute Force, with O(n²) time complexity and O(1) space complexity. We can try sorting every possible substring of the string and check how many operations it takes to make the entire string sorted. This approach is exhaustive and inefficient. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Minimum Operations to Sort a String?

Minimum Operations to Sort a String uses the following concepts: String. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Minimum Operations to Sort a String?

Clarify the constraints before diving into coding. Think about edge cases, such as already sorted strings. Explain your thought process clearly as you code.

What are common mistakes when solving Minimum Operations to Sort a String?

Not checking if the string is already sorted. Misunderstanding the constraints of sorting substrings.

#3863

Minimum Operations to Sort a String

Medium

StringHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(1)

💡

Intuition

Time O(n)Space O(1)

We can determine the minimum operations by checking the positions of the minimum and maximum characters in the string. If they are in the correct positions, we can sort the string in fewer operations.

⚙️

Algorithm

3 steps

1Step 1: Check if the string is already sorted; if yes, return 0.
2Step 2: Identify the minimum character (mn) and maximum character (mx) in the string.
3Step 3: If mn is at the start or mx is at the end (not the entire string), return 1; otherwise, return 2.

solution.py7 lines

1def minOperations(s):
2    if s == ''.join(sorted(s)):
3        return 0
4    mn, mx = min(s), max(s)
5    if s[0] == mn or s[-1] == mx:
6        return 1
7    return 2

ℹ

Complexity note: This complexity arises from scanning the string to find min and max characters, which is O(n).

1Identifying the positions of min and max characters is crucial.
2Sorting substrings can often be reduced to checking boundary conditions.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.