题解 | #最长回文子串#

let str = readline();
let start = 0;
let end = 0;
let result = '';
for(let i = 0; i < str.length; i++) {
    let len1 = aa(str, i, i);
    let len2 = aa(str, i, i + 1);
    let len = Math.max(len1, len2);
    if(len > (end - start + 1)) {
        start = i - Math.ceil(len/2) + 1;
        end = i + Math.floor(len/2);
        result = str.substr(start, len);
    }
}
// console.log('result::', result);
console.log(result.length);
function aa(str, l, r) {
    while(l >= 0 && r < str.length && str[l] == str[r]) {
        l--;
        r++;
    }
    return r - l - 1;
}