122. Best Time to Buy and Sell Stock II
Description:
Say you have an array for which the ith element is the price of a given stock on day i.
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).
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题解:
本题是在贪心算法的标签里找到的,和两周前做的第121题很像,之前那道题是只能有一次的买卖,而本题是可以多次进行买卖,但手上最多只能持有一个股票。刚开始想的时候把题目想得非常复杂,后来仔细一想其实很简单。因为可以多次进行买卖,所以可以直接只要第二天的价格比第一天的价格高就卖出去,把这个差价算到利润里,然后再判断如果再第三天的价格比第二天的高,第二天卖出后再重新买入,第三天再卖出,这和直接第一天买第三天卖是等价的,而不像121题那样必须要找到差值最大的,因为所有差值最后都被相加起来了。
代码:
class Solution {
public:
int maxProfit(vector<int>& prices) {
int profit = 0;
if (prices.size() == 0)
return 0;
for (int i = 0; i < prices.size() - 1; i++)
{
if (prices[i + 1] > prices[i])
profit += prices[i + 1] - prices[i];
}
return profit;
}
};