题目描述(Easy)
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 (i.e., buy one and sell one share of the stock multiple times).
Note: You may not engage in multiple transactions at the same time (i.e., you must sell the stock before you buy again).
题目链接
https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/description/
Example 1:
Input: [7,1,5,3,6,4]
Output: 7
Explanation: Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
Example 2:
Input: [1,2,3,4,5]
Output: 4
Explanation: Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are
engaging multiple transactions at the same time. You must sell before buying again.
Example 3:
Input: [7,6,4,3,1]
Output: 0
Explanation: In this case, no transaction is done, i.e. max profit = 0.
算法分析
低进高出，把原始序列变为差分序列，把正的价格差价加起来。
提交代码：
class Solution {
public:
int maxProfit(vector<int>& prices) {
int sum = 0;
for (int i = 1; i < prices.size(); ++i) {
int diff = prices[i] - prices[i - 1];
if (diff > 0) sum += diff;
}
return sum;
}
};