【代码随想录】day49-二、122.买卖股票的最佳时机II

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        vector<int> dp(prices.size(), 0);
        int buyPrice = prices[0];
        for (int i = 1; i < prices.size(); i ++) {
            dp[i] = dp[i-1];
            if (prices[i] > buyPrice) {
                dp[i] += prices[i] - buyPrice;
            }
            buyPrice = prices[i];       
        }
        return dp.back();
    }
};

标准dp写法：

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