class Solution {
public:
    /**
     * @param prices: Given an integer array
     * @return: Maximum profit
     */
    int maxProfit(vector<int> &prices) {
        // write your code here
        if (prices.empty()) return 0;
        int i=prices.size()-1, ans=0, maxp=prices[i];
        for (--i; i>=0; --i){
            ans=max(ans, maxp-prices[i]);
            maxp=max(maxp, prices[i]);
        }
        return ans;
    }
};