自底向上求解 想象成到第几个台阶有几个方法 斐波那契数列

public class Solution {
    public int jumpFloor(int target) {
         
        if (target<=1) return 1;
         int a =1,b=1,c=0;
        for(int i=2;i<=target;i++){
            c = a+b;
            a = b;
            b = c;
        }
        return c;
    }
}