Most Profit from Stock Prices with Cooldown

@interface Solution: NSObject
-(int)mostProfitFromStockPricesWithCooldown:(NSArray<NSNumber *> *)prices;
@end

@implementation Solution
-(int)mostProfitFromStockPricesWithCooldown:(NSArray<NSNumber *> *)prices {
    int haveStockPlusOne = 0;
    int haveStockPlusTwo = 0;
    int noStockPlusOne = 0;
    int noStockPlusTwo = 0;

    for(int i = (int)prices.count-1; i >= 0; i--) {
        int buyHere = -prices[i].intValue + haveStockPlusOne;
        int sellHere = prices[i].intValue + noStockPlusTwo;
        int holdStock = haveStockPlusOne;
        int keepDoingNothing = noStockPlusOne;

        int haveStock = MAX(sellHere, holdStock);
        int noStock = MAX(buyHere, keepDoingNothing);

        noStockPlusTwo = noStockPlusOne;
        noStockPlusOne = noStock;
        haveStockPlusTwo = haveStockPlusOne;
        haveStockPlusOne = haveStock;
    }

    int buyFirst = -prices[0].intValue + haveStockPlusTwo;
    int skipFirst = noStockPlusOne;
    return MAX(buyFirst, skipFirst);
}
@end