_409. Longest Palindrome.md

409. Longest Palindrome

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First completed : June 04, 2024

Last updated : July 01, 2024

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Related Topics : Hash Table, String, Greedy

Acceptance Rate : 55.38 %

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Solutions

• e409 Daily.c
• e409 alt a bit slower.py
• e409.py

C

e409 Daily.c

int longestPalindrome(char* s) {
    int* reference = (int*) malloc(sizeof(int) * 52);

    for (int i = 0; i < 52; i++) {
        reference[i] = 0;
    }

    int index = 0;
    while (s[index]) {
        printf("%c", s[index]);
        if (s[index] < 91) { // uppercase
            reference[s[index] - 'A']++;
        } else {
            reference[s[index] - 'a' + 26]++;
        }
        index++;
    }

    int counter = 0;
    bool odd = false;
    for (int i = 0; i < 52; i++) {
        if (reference[i] % 2 == 1) {
            odd = true;
            counter -= 1;
        }
        counter += reference[i];
    }

    free(reference);
    return counter + (odd ? 1 : 0);

}

Python

e409 alt a bit slower.py

class Solution:
    def longestPalindrome(self, s: str) -> int:
        refSet = set()

        count = 0
        for c in s :
            if c in refSet :
                refSet.remove(c)
                count += 2
            else :
                refSet.add(c)

        return count + (1 if len(refSet) > 0 else 0)

e409.py

class Solution:
    def longestPalindrome(self, s: str) -> int:
        cnt = Counter(s)
        return sum([(x // 2) * 2 for x in cnt.values()]) + (1 if sum([x % 2 for x in cnt.values()]) > 0 else 0)