LeetCode-Array-121. Best Time to Buy and Sell Stock

问题：https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
Say you have an array for which the ith element is the price of a given stock on day i.
If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.
**分析：**minPriBuy表示最小的买入值，maxPro表示最大利润值，先让minPriBuy等于数组中第一个元素值，之后遍历，如果有比它小的，则将那个值赋给它，同时计算当年的最大利润是多少，更新更大的最大利润值。
代码：

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