leetcode/5.longest-palindromic-substring.js at master · cuckon/leetcode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
/*
 * @lc app=leetcode id=5 lang=javascript
 *
 * [5] Longest Palindromic Substring
 */

// @lc code=start
/**
 * @param {string} s
 * @return {string}
 */
var longestPalindrome = function(s) {

    const res = [['', ...new Set(s.split(''))]];
    let inner;
    for(let len = 2; len <= s.length; len++) {
        res[len - 1] = []

        for(let start = 0; start <= s.length - len; start++) {
            inner = s.substr(start + 1, len - 2);
            if (s[start] == s[start + len - 1] &&
                (res[len - 3]==undefined || res[len - 3].includes(inner)))
            {
                str = s[start] + inner + s[start + len - 1];
                if (!res[len - 1].includes(str))
                    res[len - 1].push(str);
            }
        }
    }
    for (let i = res.length - 1; i >=0; i --)
        if (res[i].length)
            return res[i][res[i].length - 1]
};
// @lc code=end


function test(input, answer) {
    result = longestPalindrome(input)
    isCorrect = result == answer ? '✅' : '❌ (' + answer + ')'
    console.log(`"${input}" = ${result} : ${isCorrect}`)
}

test('a', 'a')
test('aba', 'aba')
test('daba', 'aba')
test('dabav', 'aba')