class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int minprice = 1<<31-1;
        int maxprofit = 0;
        for (int i=0;i<prices.size();i++){
            if(prices[i]<minprice){
                minprice=prices[i];
            }
            if(prices[i]-minprice>maxprofit){
                maxprofit=prices[i]-minprice;
            }
        }
        return maxprofit;
    }
};