迭代NSArray并计算差分

Question

我有一个带有不同值的卡片对象的NSArray，比方说1，2，3，5，8，10。我想确定一张卡片是否可以玩，我用卡对象的可玩属性来做这件事，这显然也有一个值属性。规则是，当一张卡是可玩的(在本例中，只有卡1是可玩的)，值只有1的牌也是可玩的。所以在上面的例子中，第二张牌也是可玩的，其余的也是不可玩的。为了清楚起见，排序可能有所不同，并不总是在上升或下降。

我想要的是遍历playerCards数组，并将1卡与数组中的所有其他卡进行比较，当差值为1时，将该卡的可玩属性设置为IsPlayable，然后再次循环，直到确定所有可玩卡。

First loop attempt (card 1 is playable):
2-1 = 1 card value 2 is playable
3-1 = 2 card value 3 is not playable
5-1 = 4 card value 5 is not playable
8-1 = 7 card value 8 is not playable
10-1 = 9 card value 10 is not playable

Second loop attempt (card 2 is now also playable):
3-2 = 1 card value 3 is playable
5-2 = 3 card value 5 is not playable
8-2 = 6 card value 8 is not playable
10-2 = 8 card value 10 is not playable

Third loop attempt (card 3 is now also playable):
5-3 = 2 card value 5 is not playable
8-3 = 5 card value 8 is not playable
10-3 = 7 card value 10 is not playable

Stop loop.

我不知道该怎么做。这就是我目前所得到的，但我迷失了方向；

for(int x = 0; x < [playerCards count]; x++) 
{    
Card *playerCard = [playerCards objectAtIndex:x];
if(playerCard.playable == IsPlayable){
something like playerCard.value-otherplayerCard.value ???}

你们能帮忙吗？

谢谢!

Answer 1

您可以将for循环放入一个while循环中，在该循环中，while循环检查是否进行了更改，而for循环是否进行了更改(或者，如果一切都完成了)。

我假设Card类有一个名为card的NSNumber

BOOL changed = YES;
NSMutableArray *playableCards = [NSMutableArray array];

while (changed) {

    changed = NO;

    for (Card *playerCard in playerCards) {
        NSNumber *card = playerCard.card;

        if (playerCard.playable == IsPlayable) {
            if (![playableCards containsObject:card]) {
                NSLog(@"Card %@ is already playable", playerCard.card);
                [playableCards addObject:card];
                changed = YES;
            }
        } else {
            NSNumber *cardUp = @(card.integerValue + 1);
            NSNumber *cardDown = @(card.integerValue - 1);

            if ([playableCards containsObject:cardUp] || [playableCards containsObject:cardDown]) {
                NSLog(@"Card %@ is being made playable", playerCard.card);
                changed = YES;
                playerCard.playable = IsPlayable;
                [playableCards addObject:card];
            }
        }
    }
}

Answer 2

这里有一个通用的编程模式，在其他地方会很有用。模式是从一些有限的信息开始，并可能添加更多的信息，从而导致更多的信息；在这种情况下，“可玩”卡最初是那些标记为可玩的卡，然后那些附近的可玩卡变得可玩，以此类推。模式是

"start with initial data"
BOOL changed = YES;

while (changed)
{
    changed = NO;
    "try to find any new information"
    if ("any new information was found")
        changed = YES;
}