Topic
Law of Violence
var a = function (start, end) {
var l = end - start;
if (l == 1) {
return 1;
}
var ll = l / 2 + start;
for (var i = start; i < ll; i++) {
if (ss.charAt(i) != ss.charAt(end - i + start - 1)) {
return 0;
}
}
return 1;
}
var ss;
/**
* @param {string} s
* @return {string}
*/
var longestPalindrome = function (s) {
ss = s;
if (s.length == 1) {
return s;
}
var max = 0;
var start;
var end;
var l = s.length;
var tl;
for (var i = 0; i < l; i++) {
if (l - i > max) {
for (var j = l; j > i; j--) {
tl = j - i;
if (tl != 0 && tl > max) {
if (a(i, j)) {
max = tl;
start = i;
end = j;
}
}
}
}
}
return s.substring(start, end);
};
https://leetcode.cn/problems/longest-palindromic-substring/submissions/
The performance can't be improved.
There is also an intermediate diffusion method that I haven't tried. It
's quite interesting to find a difficult problem to buckle!