题解 | #跳台阶#

递归：

class Solution1 {
    public int jumpFloor(int target) {
        if (target==1){
            return 1;
        }
        else if (target==2){
            return 2;
        }else {
            return jumpFloor(target-1)+jumpFloor(target-2);
        }

    }
}

dp

class Solution {
    //动态规划+滚动数组
    public int jumpFloor(int target) {
        int dp[] =new int[2];
        if (target<0){
           return -1;
        }
        else if (target==1){
            return 1;
        }
        else if (target==2){
            return 2;
        }
        else {
            dp[0]=1;
            dp[1]=2;
            int result=0;
            for (int i = 2; i <=target-1; i++) {
                result=dp[0]+dp[1];
                dp[0]=dp[1];
                dp[1]=result;
            }
            return dp[1];
        }

    }
}