LeetCode-Best Time to Buy and Sell Stock II

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 as many transactions as you like (ie, buy one and sell one share of the stock multiple times). However, you may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).

每天都可以买或卖，最多持有1股

class Solution {
public:
    int maxProfit(vector<int> &prices) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        vector<int> best;
        vector<int> next;
        best.resize(2);
        next.resize(2);
        if(prices.size()==0)return 0;
        best[0]=0;
        best[1]=-prices[0];
        next[0]=best[0];
        next[1]=best[1];
        for(int i=1;i<prices.size();i++){
            if(best[0]-prices[i]>next[1])next[1]=best[0]-prices[i];
            if(best[1]+prices[i]>next[0])next[0]=best[1]+prices[i];
            best[0]=next[0];
            best[1]=next[1];
        }
        return max(best[0],best[1]);
    }
};