题目：

题解：

#define max(a, b) ((a) < (b) ? (b) : (a))int maxProfit(int* prices, int pricesSize) {int buy1 = -prices[0], sell1 = 0;int buy2 = -prices[0], sell2 = 0;for (int i = 1; i < pricesSize; ++i) {buy1 = max(buy1, -prices[i]);sell1 = max(sell1, buy1 + prices[i]);buy2 = max(buy2, sell1 - prices[i]);sell2 = max(sell2, buy2 + prices[i]);}return sell2;
}