题解 | 跳台阶扩展问题

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param number int整型 
     * @return int整型
     */
    int jumpFloorII(int number) {
        // write code here
        vector<int> dp(number + 1,0);
        dp[0] = 0;
        dp[1] = 1;
        dp[2] = 2;
        vector<int> presum(number + 1, 0);
        presum[0] = 0;
        presum[1] = 1;
        for(int i = 3; i < number + 1; i ++){
            presum[i - 1] = presum[i - 2 ] + dp[i - 1];
            dp[i] = presum[i - 1] + 1;
            
        }
        return dp[number];
    }
};