【leetcode刷题日记】121. Best Time to Buy and Sell Stock

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 (i.e., buy one and sell one share of the stock), design an algorithm to find the maximum profit.

Note that you cannot sell a stock before you buy one.

Example 1:

Input: [7,1,5,3,6,4]
Output: 5
Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
             Not 7-1 = 6, as selling price needs to be larger than buying price.
Example 2:

Input: [7,6,4,3,1]
Output: 0
Explanation: In this case, no transaction is done, i.e. max profit = 0.

思路
本题使用动态规划思想，因为只允许进行一次股票买卖操作，所以要找出前后差值最大的一组数字

class Solution {
public:
    int maxProfit(vector& prices) {
        if(prices.size()==0)return 0;
        int size = prices.size();
        int d[size]={0};
        int minp = prices[0];
        for(int i=1;i