解析

//!  n,1
class Solution {
 public:
  int maxProfit(vector<int> &prices) {
    int minPrice = prices[0];
    int res = 0;
    for (int i = 1; i < prices.size(); ++i) {
      res = max(res, prices[i] - minPrice);
      minPrice = min(minPrice, prices[i]);
    }
    return res;
  }
};