Say you have an array for which the ith element is the price of a given stock on day i. （Easy）
Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times). However, you may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).
分析：
一次遍历，维护之前的最小值即可。
代码：
1 class Solution { 2 public: 3 int maxProfit(vector<int>& prices) { 4 if (prices.size() == 0) { 5 return 0; 6 } 7 int minPrice = prices[0]; 8 int result = 0; 9 for (int i = 1; i < prices.size(); ++i) { 10 if (prices[i] < minPrice) { 11 minPrice = prices[i]; 12 } 13 else if (prices[i] > minPrice) { 14 result = max(result,(prices[i] - minPrice)); 15 } 16 } 17 return result; 18 } 19 };
LeetCode121 Best Time to Buy and Sell Stock
原文：http://www.cnblogs.com/wangxiaobao/p/6095728.html