best-time-to-buy-and-sell-stock-iii

题目：

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).

程序：

class Solution {
public:
    int maxProfit(vector<int> &p) {
        if(p.size()==0||p.size()==1)
            return 0;
        if(p.size()==2)
            return max(0,p[1]-p[0]);
        int Max=-9999,k;
        for(k=0;k<p.size()-1;k++)
            Max=max(jisuan(p,0,k)+jisuan(p,k+1,p.size()-1),Max);
        Max=max(Max,jisuan(p,0,p.size()-1));
        return Max;
    }
    int jisuan(vector<int> &p,int i,int j)
    {
        int xl[1000],k,Min=9999,Max=-9999;
        for(k=i;k<=j;k++)
        {
            Min=min(Min,p[k]);
            xl[k]=Min;
        }
        for(k=i;k<=j;k++)
            Max=max(Max,p[k]-xl[k]);
        return Max;
    }
};