dp1

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);
        dp[0] = 0;
        dp[1] = 1;
        for(int i = 2;i <= n; i++)
            dp[i] = dp[i - 1] + dp[i - 2];
        return dp[n];
    }
};

70. 爬楼梯

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