Leetcode在线编程 Best Time to Buy and Sell Stock II

Leetcode在线编程 Best Time to Buy and Sell Stock II

题目链接

Best Time to Buy and Sell Stock II

题目描述

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).

题意

这个题意一点都不清晰- -

有每天股票的价格表，可以随时买入卖出，但是只能持有一股，即买入一股后，需要卖掉它才能购买新股，求所能获得的最大利润

解题思路

思考怎么样才能获得最大利润，整体比较困难，考虑分部分看

1）股价随天数上升的区域，

2）股价随天数下降的区域

当然不会在股价下降的区域买入卖出（亏本）

倘若在股价上升区域卖出，那么便是最大值减最小值的问题了，这好像很复杂

但仔细思考下，问题就变简单了，

假设a小于b小于c

c - a = c - b + b - a发现只要当后一天比前一天股价高的话，卖掉就必然是最大值了

sum = sum+a[j]-a[i](j>i&&a[j]>a[i]

AC代码

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