dp套路
- 确定dp数组（dp table）以及下标的含义
- 确定递推公式
- dp数组如何初始化
- 确定遍历顺序
- 举例推导dp数组
509. 斐波那契数
class Solution {
public:int fib(int n) {if (n <= 1) return n;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;int dp[n + 1];dp[0] = 0;dp[1] = 1;dp[2] = 2;for (int i = 3; i <= n; i++){dp[i] = dp[i - 2] + dp[i - 1];}return dp[n];}
};
746. 使用最小花费爬楼梯
class Solution {
public:int minCostClimbingStairs(vector<int>& cost) {int dp[cost.size() + 1];dp[0] = dp[1] = 0;for (int i = 2; i <= cost.size(); i++){dp[i] = min(cost[i - 1] + dp[i - 1], cost[i - 2] + dp[i - 2]);}return dp[cost.size()];}
};
