Best Time to Buy and Sell Stock III

最新推荐文章于 2022-04-26 10:52:27 发布

原创最新推荐文章于 2022-04-26 10:52:27 发布 · 1k 阅读

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本文介绍了一种算法，用于计算给定股票价格序列中通过至多两次买卖交易所能获得的最大利润。该算法首先从前向后遍历计算第一次买入卖出的最佳时机，再从后向前遍历确定第二次买卖的最佳时机，确保了两次交易不会重叠。

Best Time to Buy and Sell Stock III:

Say you have an array for which the i^th 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).

class Solution {
public:
    int maxProfit(vector<int> &prices) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        
    	int n=prices.size();
		vector<int> before(n,0);
		int bp=INT_MAX;
		int profit=0;
		for(int i=0;i<n;i++)
		{
			if ( prices[i]>bp )
				profit=max(profit,prices[i]-bp);
			else
				bp=prices[i];
			before[i]=profit;
		}
		int maxProfit=profit;
		bp=INT_MIN;
		profit=0;
		for(int i=n-1;i>=0;i--)
		{
			if ( prices[i] < bp )
				profit=max(profit,bp-prices[i]);
			else
				bp=prices[i];
			if ( i>0 )
				maxProfit=max(maxProfit,profit+before[i-1]);
		}
		return maxProfit;
	}
};