309. Best Time to Buy and Sell Stock with Cooldown

leetcode309.swift

class Solution {
    func maxProfit(_ prices: [Int]) -> Int {
        guard !prices.isEmpty else {
            return 0
        }

        var hold = [Int](repeating: Int.min, count: prices.count + 1)
        var sell = [Int](repeating: 0, count: prices.count + 1)
        var cooldown = [Int](repeating: 0, count: prices.count + 1)
        
        for day in 1...prices.count {
            hold[day] = max(hold[day-1], cooldown[day-1] - prices[day-1])
            sell[day] = hold[day-1] + prices[day-1]
            cooldown[day] = max(cooldown[day-1],sell[day-1])
        }

        return max(cooldown[prices.count],hold[prices.count],sell[prices.count])
    }
}