代码随想录算法训练营第三十八天 | LeetCode509. 斐波那契数、70. 爬楼梯、746. 使用最小花费爬楼梯

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一、509. 斐波那契数

解题代码C++：

class Solution {
public:int fib(int N) {if (N <= 1) return N;int dp[2];dp[0] = 0;dp[1] = 1;for (int i = 2; i <= N; i++) {int sum = dp[0] + dp[1];dp[0] = dp[1];dp[1] = sum;}return dp[1];}
};

题目链接/文章讲解/视频讲解：
https://programmercarl.com/0509.%E6%96%90%E6%B3%A2%E9%82%A3%E5%A5%91%E6%95%B0.html

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二、70. 爬楼梯

解题代码C++：

class Solution {
public:int climbStairs(int n) {if (n <= 1) return n;int dp[3];dp[1] = 1;dp[2] = 2;for (int i = 3; i <= n; i++) {int sum = dp[1] + dp[2];dp[1] = dp[2];dp[2] = sum;}return dp[2];}
};

题目链接/文章讲解/视频讲解：
https://programmercarl.com/0070.%E7%88%AC%E6%A5%BC%E6%A2%AF.html

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三、746. 使用最小花费爬楼梯

解题代码C++：

class Solution {
public:int minCostClimbingStairs(vector<int>& cost) {int dp0 = 0;int dp1 = 0;for (int i = 2; i <= cost.size(); i++) {int dpi = min(dp1 + cost[i - 1], dp0 + cost[i - 2]);dp0 = dp1; // 记录一下前两位dp1 = dpi;}return dp1;}
};

题目链接/文章讲解/视频讲解：
https://programmercarl.com/0746.%E4%BD%BF%E7%94%A8%E6%9C%80%E5%B0%8F%E8%8A%B1%E8%B4%B9%E7%88%AC%E6%A5%BC%E6%A2%AF.html