在 Objective-C 中检查字符串中的相同字符

发布于 2024-12-23 23:43:51 字数 559 浏览 10 评论 0原文

我有一个字符串数组，我想从中仅提取具有唯一字符集的字符串。（例如，“asdf”和“fdsa”将被视为多余）。这是我目前正在使用的方法：

NSMutableArray *uniqueCharSets = [[NSMutableArray alloc] init];
NSMutableArray *uniqueStrings = [[NSMutableArray alloc] init];        

for (NSString *_string in unique) {
    NSCharacterSet *_charSet = [NSCharacterSet characterSetWithCharactersInString:_string];
    if (![uniqueCharSets containsObject:_charSet]) {
        [uniqueStrings addobject:_string];
        [uniqueCharSets addObject:_charSet];
    }
}

这似乎可行，但它非常慢并且占用资源。有人能想出更好的方法来做到这一点吗？

原文

I have an array of strings, from which I would like to extract only those with unique character sets. (For example, "asdf" and "fdsa" would be considered redundant). This is the method I am currently using:

NSMutableArray *uniqueCharSets = [[NSMutableArray alloc] init];
NSMutableArray *uniqueStrings = [[NSMutableArray alloc] init];        

for (NSString *_string in unique) {
    NSCharacterSet *_charSet = [NSCharacterSet characterSetWithCharactersInString:_string];
    if (![uniqueCharSets containsObject:_charSet]) {
        [uniqueStrings addobject:_string];
        [uniqueCharSets addObject:_charSet];
    }
}

This seems to work, but it's very slow and resource-intensive. Can anyone think of a better way to do this?

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-小熊_ 2024-12-30 23:43:51

使用 NSDictionary，将每个字符串按字典顺序排序的等效项映射到输入字符串的 NSArray：（例如 adfs => [afsd , asdf, ...])
遍历字典，打印出仅具有单元素数组值的键（或其值）

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花开浅夏 2024-12-30 23:43:51

我只是整理了一个简单的例子来说明我将如何处理这个问题，但事实证明它比你最初预期的更奇怪。其一，NSCharacterSet 没有实现相等性来检查内容。它仅使用指针值。基于此，您的示例将无法正常工作。

我的方法是使用 NSSet 来为我们处理这些哈希值。

@interface StringWrapper : NSObject
@property (nonatomic, copy) NSString *string;
@property (nonatomic, copy) NSData *charSetBitmap;
- (id)initWithString:(NSString*)aString;
@end

@implementation StringWrapper
@synthesize string, charSetBitmap;

- (id)initWithString:(NSString*)aString;
{
    if ((self = [super init]))
    {
        self.string = aString;
    }
    return self;
}

- (void)setString:(NSString *)aString;
{
    string = [aString copy];
    self.charSetBitmap = [[NSCharacterSet characterSetWithCharactersInString:aString] bitmapRepresentation];
}

- (BOOL)isEqual:(id)object;
{
    return [self.charSetBitmap isEqual:[object charSetBitmap]];
}

- (NSUInteger)hash;
{
    return [self.charSetBitmap hash];
}

@end

int main (int argc, const char * argv[])
{
    @autoreleasepool {
        NSMutableSet *stringWrappers = [[NSMutableSet alloc] init];
        NSArray *strings = [NSArray arrayWithObjects:@"abc",@"aaabcccc",@"awea",@"awer",@"abcde", @"ehra", @"QWEQ", @"werawe", nil];
        for (NSString *str in strings)
            [stringWrappers addObject:[[StringWrapper alloc] initWithString:str]];

        NSArray *uniqueStrings = [stringWrappers valueForKey:@"string"];
        NSLog(@"%@", uniqueStrings);

    }
    return 0;
}

代码非常简单。我们创建一个容器对象来缓存字符集位图表示的结果。我们使用位图表示是因为 NSData 适当地实现了 isEqual:。

I just put together a quick example of how I would approach this, but it turns out that it is more, odd, than you first expect. For one, NSCharacterSet doesn't implement equality to check contents. It only uses the pointer value. Based on this your example will NOT work properly.

My approach is to use an NSSet to deal with the hashing of these for us.

@interface StringWrapper : NSObject
@property (nonatomic, copy) NSString *string;
@property (nonatomic, copy) NSData *charSetBitmap;
- (id)initWithString:(NSString*)aString;
@end

@implementation StringWrapper
@synthesize string, charSetBitmap;

- (id)initWithString:(NSString*)aString;
{
    if ((self = [super init]))
    {
        self.string = aString;
    }
    return self;
}

- (void)setString:(NSString *)aString;
{
    string = [aString copy];
    self.charSetBitmap = [[NSCharacterSet characterSetWithCharactersInString:aString] bitmapRepresentation];
}

- (BOOL)isEqual:(id)object;
{
    return [self.charSetBitmap isEqual:[object charSetBitmap]];
}

- (NSUInteger)hash;
{
    return [self.charSetBitmap hash];
}

@end

int main (int argc, const char * argv[])
{
    @autoreleasepool {
        NSMutableSet *stringWrappers = [[NSMutableSet alloc] init];
        NSArray *strings = [NSArray arrayWithObjects:@"abc",@"aaabcccc",@"awea",@"awer",@"abcde", @"ehra", @"QWEQ", @"werawe", nil];
        for (NSString *str in strings)
            [stringWrappers addObject:[[StringWrapper alloc] initWithString:str]];

        NSArray *uniqueStrings = [stringWrappers valueForKey:@"string"];
        NSLog(@"%@", uniqueStrings);

    }
    return 0;
}

The code is pretty straightforward. We create a container object to cache the results of the character set's bitmap representation. We use the bitmap representation because NSData implements isEqual: appropriately.

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