Best Time to Buy and Sell Stock III

最新推荐文章于 2022-04-26 10:52:27 发布

spongewxy

最新推荐文章于 2022-04-26 10:52:27 发布

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分类专栏： LeetCode

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本文介绍了一个算法，旨在解决给定股票价格序列中寻找两次交易的最大收益问题。通过使用动态规划和预处理技术，该算法能在O(n)的时间复杂度内找到最佳的买卖策略。

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Say you have an array for which the ith element is the price of a given stock on day i.

Design an algorithm to find the maximum profit. You may complete at most two transactions.

Note:
You may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).

/* 枚举+预处理 */

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int n = prices.size();
        if(n <= 1) return 0;
        vector<int> minv(n);
        vector<int> maxv(n);
        vector<int> dp1(n);
        vector<int> dp2(n);
        int ans = 0;
        minv[0] = prices[0];
        dp1[0] = 0;
        for(int i = 1; i < n; ++i) {
            dp1[i] = max(dp1[i-1], prices[i] - minv[i-1]);
            minv[i] = min(minv[i-1], prices[i]);
        }
        maxv[n-1] = prices[n-1];
        dp2[n-1] = 0;
        for(int i = n - 2; i >= 0; --i) {
            dp2[i] = max(dp2[i+1], maxv[i+1] - prices[i]);
            maxv[i] = max(maxv[i+1], prices[i]);
        }
        for(int i = 0; i < n; ++i) {
            ans = max(ans, dp1[i] + dp2[i]);
        }
        return ans;
    }
};