53. 连续字母长度

const readline = require('readline');
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});
let lines = [];
rl.on('line', function(line) {
    lines.push(line);
    if (lines.length === 2) {
        let k = parseInt(lines[1]);
        let str = lines[0];
        let obj = {};
        let s = str[0];
        let count = 1;
        for(let i=1; i<str.length; i++) {
            if (str[i] === str[i-1]) {
                count++;
            } else {
                obj[str[i-1]] = Math.max((obj[str[i-1]] || 0), count);
                s = str[i];
                count = 1;
            }
        }
        let ans = [];
        for(let i in obj) {
            ans.push({n: i, v: obj[i]});
        }
        ans.sort((a,b) => b.v - a.v);
        console.log(ans[k - 1] ? ans[k - 1].v : -1);
    }
});