409. Longest Palindrome

[Tcdian]

409. Longest Palindrome

给定一个包含大写字母和小写字母的字符串，找到通过这些字母构造成的最长的回文串。

在构造过程中，请注意区分大小写。比如 "Aa" 不能当做一个回文字符串。

Example

Input:
"abccccdd"

Output:
7

Explanation:
One longest palindrome that can be built is "dccaccd", whose length is 7.

Note

• Assume the length of given string will not exceed 1,010.

[Tcdian]

Solution

• JavaScript Solution

/**
 * @param {string} s
 * @return {number}
 */
var longestPalindrome = function(s) {
    const cache = new Map();
    let result = 0;
    let hasSingleLetter = false;
    for (let i = 0; i < s.length; i++) {
        cache.set(s[i], (cache.get(s[i]) || 0) + 1);
    }
    cache.forEach((letter) => {
        result += (letter >> 1) * 2;
        if (letter % 2 === 1) {
            hasSingleLetter = true;
        }
    });
    return result + (hasSingleLetter ? 1 : 0);
};

• TypeScript Solution

function longestPalindrome(s: string): number {
    const cache: Map<string, number> = new Map();
    let result = 0;
    let hasSingleLetter = false;
    for (let i = 0; i < s.length; i++) {
        cache.set(s[i], (cache.get(s[i]) || 0) + 1);
    }
    cache.forEach((letter) => {
        result += (letter >> 1) * 2;
        if (letter % 2 === 1) {
            hasSingleLetter = true;
        }
    });
    return result + (hasSingleLetter ? 1 : 0);
};