题解 | #密码截取#

const rl = require("readline").createInterface({ input: process.stdin });
let num=[];
rl.on("line", (line) => {
    let arr = line.split("");
    // console.log(arr);
    for (let i = arr.length - 1; i >= 0; i--) {
        // ABA型
        let j = i - 1;
        let k = i + 1;
        let sum = 1;
        while (arr[j] == arr[k]) {
            if (arr.indexOf(arr[j]) + 1 && arr.indexOf(arr[k] + 1)) {
                sum += 2;
                j--;
                k++;
            } else {
                break;
            }
        }
        num.push(sum);
        // ABBA型
        let m = i - 2;
        let n = i + 1;
        let sum2 = 1;
        if (arr[i] == arr[i - 1]) {
            sum2 = 2;
            while (arr[m] == arr[n]) {
                if (arr.indexOf(arr[m]) + 1 && arr.indexOf(arr[n]) + 1) {
                    sum2 += 2;
                    m--;
                    n++;
                } else {
                    break;
                }
            }
        }
        num.push(sum2)
    }
    // console.log(num)
    let result = Math.max(...num);
    console.log(result)
});