题解 | #跳台阶#

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

function numWays(n) {
    if (n < 2) return 1;
    let pre = 1, cur = 2;
    for (let i=3;i<=n;i++) {
        let tmp = pre + cur;
        pre = cur;
        cur = tmp;
    }
    return cur;
}

void async function () {
    // Write your code here
    while(line = await readline()){
        const n = parseInt(line);
        console.log(numWays(n))
    }
}()