309. Best Time to Buy and Sell Stock with Cooldown.java

class Solution {
    public int maxProfit(int[] prices) {
         if(prices == null || prices.length <= 1) return 0;
​
            int b0 = -prices[0], b1 = b0;
            int s0 = 0, s1 = 0, s2 = 0;
​
            for(int i = 1; i < prices.length; i++) {
                b0 = Math.max(b1, s2 - prices[i]);
                s0 = Math.max(s1, b1 + prices[i]);
                b1 = b0; s2 = s1; s1 = s0; 
            }
            return s0;   
    }
}