309. Best Time to Buy and Sell Stock with Cooldown

309. Best Time to Buy and Sell Stock with Cooldown

题目链接：https://leetcode.com/problems...

dp来解，要用两个dp array分别表示现在的操作是buy还是sell，优化空间用滚动数组，或者几个int

public class Solution {
    public int maxProfit(int[] prices) {
        if(prices.length == 0) return 0;
        /* buy[i] = Math.max(sell[i-2]-prices[i], buy[i-1])
         * sell[i] = Math.max(sell[i-1], buy[i-1] + prices[i])
         */
        int preBuy = Integer.MIN_VALUE, curBuy = Integer.MIN_VALUE;
        int preSell = 0, curSell = 0;
        for(int price : prices) {
            preBuy = curBuy;
            curBuy = Math.max(preSell - price, preBuy);
            preSell = curSell;
            curSell = Math.max(preSell, preBuy + price);
        }
        
        return curSell;
    }
}