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;

const MOD = 998244353;
function getStepNum(num) {
    let a = 1;
    b = 1;
    if (num == 1) return 1;
    for (let i = 3; i <= num; i++) {
        let c = (a + b) % MOD;
        a = b;
        b = c;
    }
    return b;
}
void (async function () {
    // Write your code here
    while ((line = await readline())) {
        const res = getStepNum(line)
        console.log(res)
    }
})();