LeetCode:Best Time to Buy and Sell Stock

Best Time to Buy and Sell Stock

Total Accepted: 80325 Total Submissions: 231655 Difficulty: Medium

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

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 Array Dynamic Programming

思路：

1.先求后项与前项的差分数组diff[]；

2.再利用状态转移方程：dp[i] = max(diff[i], dp[i-1] + diff[i]);求dp；

3.求dp数组中的最大值。

code:

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