题解 | #密码截取#

const readline = require("readline");

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});
rl.on("line", function (line) {
    solution(line);
});
let maxLen = 0;
function solution(line: string) {
    for (let index = 0; index < line.length; index++) {
        const element = line[index];
        expand([index, index + 1], line);
        expand([index, index + 2], line);
    }
    console.log(maxLen);
}

function expand([start, end]: [number, number], line: string) {
    if (!(start >= 0 && end <= line.length)) {
        return;
    }
    let subStr = line.substring(start, end);
    let subStrReversed = subStr.split("").reverse().join("");
    if (subStr === subStrReversed) {
        maxLen = Math.max(maxLen, subStr.length);
        return expand([start - 1, end + 1], line);
    }
}