[leetcode] 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 minVal=0x7FFFFFFF;
        int prev=0;
        int next=0;
        int max=0;
        int i;
        int count=prices.size();
        int *max2=new int[count];
        max2[count-1]=0;
        for(i=count-2 ; i>=0 ; i--){
            if(prices[i+1]>max)
                max=prices[i+1];
            if(max-prices[i]>next)
                next=max-prices[i];
            max2[i]=next;
        }
        max=0;
        for(i=-1 ; i<count-2 ; i++){
            if(i>=0){
                if(prices[i]<minVal)
                    minVal=prices[i];
                if(prices[i]-minVal>prev)
                    prev=prices[i]-minVal;
            }
            if(prev+max2[i+1]>max)
                max=prev+max2[i+1];
        }
        return max;           
    }
};