Best Time to Buy and Sell Stock

题目：

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.

接口：

class Solution {
public:
    /**
     * @param prices: Given an integer array
     * @return: Maximum profit
     */
    int maxProfit(vector<int> &prices) {
        // write your code here

    }
};

分析：

这道题目是BT2B类里面的基础题，只有一手买入和一手卖出，只要维护minPrice和maxProfit就可以解决问题

解答：

class Solution {
public:
    /**
     * @param prices: Given an integer array
     * @return: Maximum profit
     */
    int maxProfit(vector<int> &prices) {
        // write your code here
        if (prices.size() <= 1) {
            return 0;
        }

        int minPrice = INT_MAX;
        int maxProfit = 0;

        for (int i = 0; i < prices.size(); i++) {
            minPrice = min(minPrice, prices[i]);
            maxProfit = max(maxProfit, prices[i] - minPrice);
        }

        return maxProfit;
    }
};