509. 斐波那契数

class Solution {
public:int fib(int n){if (n==0) return 0;if (n==1) return 1;vector<int> dp(n+1, 0);dp[0] = 0;dp[1] = 1;for (int i=2; i<n+1;i++){dp[i] = dp[i-1] + dp[i-2];}return dp[n];}
};

70. 爬楼梯

class Solution {
public:int climbStairs(int n) {vector<int> ans(n+1);ans[0]=1;ans[1]=1;for (int i=2; i<n+1; i++){ans[i] = ans[i-1] + ans[i-2];}return ans[n];}
};

746. 使用最小花费爬楼梯

class Solution {
public:int minCostClimbingStairs(vector<int>& cost) {int n = cost.size();vector<int> dp(n+1);dp[0]=0;dp[1]=0;for (int i=2; i<n+1;i++){dp[i] = min(dp[i-1]+cost[i-1], dp[i-2]+cost[i-2]);}return dp[n];}
};