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[leetcode] problem 131 – palindrome partitioning

admin 11月 13, 2020 0

Given a string s, partition s such that every substring of the partition is a palindrome.

Return all possible palindrome partitioning of s.

Example:

Input: “aab”

Output:

[
  ["aa","b"],
  ["a","a","b"]
]

Code

public List<List<String>> partition(String s) {
    List<List<String>> result = new ArrayList<>();

    partitionHelper(result, new ArrayList<>(), s, 0);

    return result;
}

private void (List<List<String>> result, List<String> palindrome, String s, int idx) {
    if (idx == s.length()) {
        result.add(new ArrayList<>(palindrome));
        return;
    }
    
    for (int i = idx; i < s.length(); i++) {
        if (isPalindrome(s, idx, i)) {
            palindrome.add(s.substring(idx, i + 1));
            partitionHelper(result, palindrome, s, i + 1);
            palindrome.remove(palindrome.size() - 1);
        }
    }
}

private boolean isPalindrome(String s, int start, int end) {
    while (start < end) {
        if (s.charAt(start) != s.charAt(end))
            return false;

        start++;
        end--;
    }

    return true;
}