LeetCode 123. Best Time to Buy and Sell Stock III

最多只能交易两次 求最大可以获得利润

class Solution {
  public int maxProfit(int[] prices) {
    int t1Cost = Integer.MAX_VALUE, 
        t2Cost = Integer.MAX_VALUE;
    int t1Profit = 0,
        t2Profit = 0;

    for (int price : prices) {
        // the maximum profit if only one transaction is allowed
        t1Cost = Math.min(t1Cost, price); //成本为正 取最小
        t1Profit = Math.max(t1Profit, price - t1Cost); //维护一个最大的利润值
        // reinvest the gained profit in the second transaction
        t2Cost = Math.min(t2Cost, price - t1Profit); //成本依然取最小 但是不一样的是我们因为之前赚了t1Profit的钱 因此要从成本里面扣掉
        t2Profit = Math.max(t2Profit, price - t2Cost); //利润既然取最大
    }

    return t2Profit;
  }
}

这个答案就是完完全全从LC21演变过来的