0714.go

// Source: https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee
// Title: Best Time to Buy and Sell Stock with Transaction Fee
// Difficulty: Medium
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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
//
// Constraints:
//
//   1 <= prices.length <= 5 * 10^4
//   1 <= prices[i] < 5 * 10^4
//   0 <= fee < 5 * 10^4
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

import (
	"math"
)

func maxProfit(prices []int, fee int) int {
	bVal := math.MinInt32
	sVal := 0

	for _, price := range prices {
		bVal, sVal = _max(bVal, sVal-price), _max(sVal, bVal+price-fee)
	}

	return sVal
}

func _max(a, b int) int {
	if a > b {
		return a
	}
	return b
}