Leetcode 70. Climbing Stairs 爬楼梯 (递归,记忆化，动态规划)

class Solution {
public:
    int climbStairs(int n) {
        this->n = n;

        memo = new int[n+2];
        for(int i=0;i<n+2;i++){
            memo[i] = -1;
        }

        return recursiveClimbing(0);
    }

    int recursiveClimbing(int currentStep){
        if(memo[currentStep]!=-1){
            return memo[currentStep];
        }

        if(currentStep==n){
            return 1;
        }
        if(currentStep>n){
            return 0;
        }
        memo[currentStep] = recursiveClimbing(currentStep+1) + recursiveClimbing(currentStep+2);    
        return memo[currentStep];
    }
private:
    int n;
    int total = 0;
    int *memo;
};