买卖股票的最佳时机

class Solution {
public:
    int maxProfit(vector<int> &prices) {
        using namespace std;
           int profit=0;
        if(prices.size()<2)
        {
            return profit;
        }
        else
        {
            int lost=prices[0];
            for(int i=1;i<prices.size();i++)
            {
                profit=max(profit,prices[i]-lost);
                lost=min(lost,prices[i]);
            }
        }
        return profit;
    }
};