编辑代码

//递归
function recursiveStairs(n) {
    if (n <= 1) {
        return 1;
    }
    return recursiveStairs(n - 1) + recursiveStairs(n - 2);
}

//递推
function iterativeStairs(n) {
    if (n <= 1) {
        return 1;
    }
    let prev = 1;
    let current = 1;
    for (let i = 2; i <= n; i++) {
        const temp = current;
        current = prev + current;
        prev = temp;
    }
    return current;
}