买卖股票的最佳时机II

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        if(size(prices)==0) return 0;
        int i,s=0;
        for(i=0;i<size(prices)-1;i++)
            if(prices[i]<prices[i+1]) s+=prices[i+1]-prices[i];
        return s;
    }
};