How do you solve Find Longest Awesome Substring on LeetCode?

Find Longest Awesome Substring (LeetCode #1542) can be solved using Brute Force. The optimal approach is Brute Force with O(n²) time complexity and O(1) space complexity. Key insight: The brute force approach involves checking every possible substring of the given string to see if it can be rearranged into a palindrome. This is simple but inefficient, as it requires examining all combinations.

What algorithm or data structure is used to solve Find Longest Awesome Substring?

Find Longest Awesome Substring uses the following concepts: Hash Table, String, Bit Manipulation. The recommended patterns to study are: .

Find Longest Awesome Substring — LeetCode #1542 (Hard)

Tags: Hash Table, String, Bit Manipulation

Related patterns:

Brute Force approach

Time complexity: O(n²). Space complexity: O(1).

The brute force approach involves checking every possible substring of the given string to see if it can be rearranged into a palindrome. This is simple but inefficient, as it requires examining all combinations.

The complexity is O(n²) because we are generating all substrings (O(n²) combinations) and checking each for palindrome potential, which takes O(n) time for counting.

Step 1: Generate all possible substrings of the string.
Step 2: For each substring, count the frequency of each digit.
Step 3: Check if the substring can be rearranged into a palindrome by ensuring at most one digit has an odd count.
Step 4: Keep track of the maximum length of valid substrings.

For s = '3242415': 1. Substring '3': count = [1,0,0,0,0,0,0,0,0,0], odd_count = 1, max_length = 1 2. Substring '32': count = [1,1,0,0,0,0,0,0,0,0], odd_count = 2, max_length = 1 3. Substring '324': count = [1,1,1,0,0,0,0,0,0,0], odd_count = 3, max_length = 1 4. Substring '3242': count = [1,1,2,0,0,0,0,0,0,0], odd_count = 1, max_length = 4 5. Substring '32424': count = [1,1,3,0,0,0,0,0,0,0], odd_count = 1, max_length = 5 6. Substring '3242415': count = [1,1,3,1,0,0,0,0,0,0], odd_count = 2, max_length = 5

#1542

Find Longest Awesome Substring

Hard

Hash Table↗String↗Bit Manipulation↗

LeetCode ↗

Approaches

💡

Intuition

Time O(n²)Space O(1)

⚙️

Algorithm

4 steps

1Step 1: Generate all possible substrings of the string.
2Step 2: For each substring, count the frequency of each digit.
3Step 3: Check if the substring can be rearranged into a palindrome by ensuring at most one digit has an odd count.
4Step 4: Keep track of the maximum length of valid substrings.

solution.py12 lines

1def longestAwesome(s):
2    max_length = 0
3    for i in range(len(s)):
4        for j in range(i, len(s)):
5            substring = s[i:j+1]
6            count = [0] * 10
7            for char in substring:
8                count[int(char)] += 1
9            odd_count = sum(1 for c in count if c % 2 != 0)
10            if odd_count <= 1:
11                max_length = max(max_length, j - i + 1)
12    return max_length

ℹ

Complexity note: The complexity is O(n²) because we are generating all substrings (O(n²) combinations) and checking each for palindrome potential, which takes O(n) time for counting.

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