牛客网：NC68 跳台阶

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