714 Best Time to Buy and Sell Stock with Transaction Fee

Problem

Your are given an array of integers prices, for which the i-th element is the price of a given stock on day i; and a non-negative integer fee representing a transaction fee.

You may complete as many transactions as you like, but you need to pay the transaction fee for each transaction. You may not buy more than 1 share of a stock at a time (ie. you must sell the stock share before you buy again.)

Return the maximum profit you can make.

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.

Note:

0 < prices.length <= 50000. 0 < prices[i] < 50000. 0 <= fee < 50000.

Solutions

class Solution {
    public int maxProfit(int[] prices, int fee) {
        int[][] dp = new int[prices.length + 1][2];
        int res = 0;
        dp[0][0] = 0;
        dp[0][1] = Integer.MIN_VALUE;
        for (int i = 0; i < prices.length; i ++) {
            dp[i + 1][0] = Math.max(dp[i][0], dp[i][1] + prices[i]);
            dp[i + 1][1] = Math.max(dp[i][1], dp[i][0] - prices[i] - fee);
            res = Math.max(res, dp[i + 1][0]);
            res = Math.max(res, dp[i + 1][1]);
        }
        return res;
    }
}