LeetCode-in-Java

1147. Longest Chunked Palindrome Decomposition

Hard

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

• subtexti is a non-empty string.
• The concatenation of all the substrings is equal to text (i.e., subtext1 + subtext2 + ... + subtextk == text).
• subtexti == subtextk - i + 1 for all valid values of i (i.e., 1 <= i <= k).

Return the largest possible value of k.

Example 1:

Input: text = “ghiabcdefhelloadamhelloabcdefghi”

Output: 7

Explanation: We can split the string on “(ghi)(abcdef)(hello)(adam)(hello)(abcdef)(ghi)”.

Example 2:

Input: text = “merchant”

Output: 1

Explanation: We can split the string on “(merchant)”.

Example 3:

Input: text = “antaprezatepzapreanta”

Output: 11

Explanation: We can split the string on “(a)(nt)(a)(pre)(za)(tpe)(za)(pre)(a)(nt)(a)”.

Constraints:

• 1 <= text.length <= 1000
• text consists only of lowercase English characters.

Solution

public class Solution {
    public int longestDecomposition(String text) {
        int n = text.length();
        int l = 0;
        int r = n - 1;
        int len = 1;
        int ans = 0;
        String lft;
        String rit;
        boolean perfectSubstring = false;
        while (l + len <= r - len + 1) {
            lft = text.substring(l, l + len);
            rit = text.substring(r - len + 1, r + 1);
            if (lft.equals(rit)) {
                ans += 2;
                if (l + len == r - len + 1) {
                    perfectSubstring = true;
                    break;
                }
                l = l + len;
                r = r - len;
                len = 1;
            } else {
                len++;
            }
        }
        if (!perfectSubstring) {
            ans++;
        }
        return ans;
    }
}

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