Longest Chunked Palindrome Decomposition — LeetCode 1147 Python Solution

The problem

You are given a string text. You should split it to k substrings (subtext1, subtext2, ..., subtextk) such that: subtexti is a non-empty string.

Example

Input

text = "ghiabcdefhelloadamhelloabcdefghi"

Output

7

Explanation

We can split the string on "(ghi)(abcdef)(hello)(adam)(hello)(abcdef)(ghi)".

Python solution

class Solution:
    def longestDecomposition(self, text: str) -> int:
        ans = 0
        i, j = 0, len(text) - 1
        while i <= j:
            k = 1
            ok = False
            while i + k - 1 < j - k + 1:
                if text[i : i + k] == text[j - k + 1 : j + 1]:
                    ans += 2
                    i += k
                    j -= k
                    ok = True
                    break
                k += 1
            if not ok:
                ans += 1
                break
        return ans

Complexity

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 1147. Longest Chunked Palindrome Decomposition is filed here because LeetCode tags it Two Pointers, which is the vocabulary this hub collects.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

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