123. Best Time to Buy and Sell Stock III
题目
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).
解析
//Buy and Sell Stock iii
class Solution_123 {
public:
int maxProfit(vector<int> &prices) {
//1.买一次相当于减一个数，
//2.买卖两次维持当前最大的收益
int buy1 = INT_MIN, sell1 = 0;
int buy2 = INT_MIN, sell2 = 0;
for (int i = 0; i < prices.size();i++)
{
buy1 = max(buy1, -prices[i]);
sell1 = max(sell1, buy1 + prices[i]); //一次买卖现有的收益
buy2 = max(buy2, sell1 - prices[i]); //又要使用一些钱
sell2 = max(sell2, buy2 + prices[i]);
}
return sell2;
}
};