714. Best Time to Buy and Sell Stock with Transaction Fee

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# 題目敘述

You are given an array prices where prices[i] is the price of a given stock on the ith day, and an integer fee representing a transaction fee.

Find the maximum profit you can achieve. You may complete as many transactions as you like, but you need to pay the transaction fee for each transaction.

Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).

# Example 1

Input: prices = [1,3,2,8,4,9], fee = 2
Output: 8
Explanation: The maximum profit can be achieved by:

• Buying at prices[0] = 1
• Selling at prices[3] = 8
• Buying at prices[4] = 4
• Selling at prices[5] = 9
  The total profit is ((8 - 1) - 2) + ((9 - 4) - 2) = 8.

# Example 2

Input: prices = [1,3,7,5,10,3], fee = 3
Output: 6

# 解題思路

# Solution

class Solution {

    public int maxProfit(int[] prices, int fee) {

        int ans = 0;

        int buy = -prices[0];

        for (int price : prices) {

            int temp = buy;

            buy = Math.max(buy, ans - price);

            ans = Math.max(ans, temp + price - fee);

        }

        return ans;

    }

}