题解 | #跳台阶#

class Solution {
public:
    int jumpFloor(int n) {
        if (n <= 2) return n;
        int n1 = 1, n2 = 2, n3 = 0;
        for (int i = 3; i <= n; ++i) {
            n3 = n1 + n2;
            n1 = n2;
            n2 = n3;
        }
        return n3;
    }
};