查找哪个数组的计数最高

Question

如何找到三个数组中最长（最高计数）的数组？

背景：

我有一个运行良好的匹配函数 - 三个带有布尔值的字典包含用户首选项，一篇文章有​​三个标签类别，该函数检查标签 A 是否在字典 A 中打开，标签 B 是否在字典 B 中打开，等等

现在的要求是标签A中可能有N个条目，标签B中可能有N个条目，等等

这样三个标签数组中的每一个都可以有不同的长度，我能想到的最简单的方法是找到最长的数组（包含最多的条目）从 ArrayA、ArrayB 和ArrayC

这是我原来的工作循环，

for (id myArrayElement in storyArray) {

    NSString *myString = [NSString stringWithString:[myArrayElement industryA]];
    NSString *myIssue = [NSString stringWithString:[myArrayElement issueA]];
    NSString *myService = [NSString stringWithString:[myArrayElement serviceA]];

    if (
        [prefsDictionary valueForKeyPath:[NSString stringWithFormat:@"Industries.%@", myString]] || 
        [prefsDictionary valueForKeyPath:[NSString stringWithFormat:@"Issues.%@", myIssueElement]] || 
        [prefsDictionary valueForKeyPath:[NSString stringWithFormat:@"Services.%@", myService]]
        ) {

        // One of the story's tags matches a key in one of the corresponding dictionaries
        // Look up what this preference is set to

        NSString *keyvalue = [[prefsDictionary valueForKey:@"Industries"] valueForKey:myString];
        NSString *Issuesvalue = [[prefsDictionary valueForKey:@"Issues"] valueForKey:myIssueElement];
        NSString *Servicevalue = [[prefsDictionary valueForKey:@"Services"] valueForKey:myService];

        if (
            [keyvalue isEqualToString:@"1"] || 
            [Issuesvalue isEqualToString:@"1"] || 
            [Servicevalue isEqualToString:@"1"]
            ) {

            // It's a match, add the story
            [self.favList addObject:myArrayElement];
        }

    } // prefsDictionary End if

我认为最好的方法是执行此操作，其中三个输入可以是任意长度的数组，

for (id myArrayElement in delegate.storyArray) {

    NSArray *industyArr = [[myArrayElement industryA] componentsSeparatedByString:@"|"];
    NSArray *issueArr = [[myArrayElement issueA] componentsSeparatedByString:@"|"];
    NSArray *serviceArr = [[myArrayElement serviceA] componentsSeparatedByString:@"|"];

    // We need to find longest array
    // Pad the shorter arrays, or use if ([array count] >= 4) {id obj = [scores objectAtIndex:3];}
    // Then loop using the largest array length

    for (loop longest array length) {

               // get nth entry in industyArr... thisIndustry
               // get nth entry in issueArr...   thisIssue
               // get nth entry in serviceArr... thisService

        if (
            [prefsDictionary valueForKeyPath:[NSString stringWithFormat:@"Industries.%@", thisIndustry]] || 
            [prefsDictionary valueForKeyPath:[NSString stringWithFormat:@"Issues.%@", thisIssue]] || 
            [prefsDictionary valueForKeyPath:[NSString stringWithFormat:@"Services.%@", thisService]]
            ) {

            // One of the story's tags matches a key in one of the corresponding dictionaries

            NSString *keyvalue = [[prefsDictionary valueForKey:@"Industries"] valueForKey:thisIndustry];
            NSString *Issuesvalue = [[prefsDictionary valueForKey:@"Issues"] valueForKey:thisIssue];
            NSString *Servicevalue = [[prefsDictionary valueForKey:@"Services"] valueForKey:thisService];

            if (
                [keyvalue isEqualToString:@"1"] || 
                [Issuesvalue isEqualToString:@"1"] || 
                [Servicevalue isEqualToString:@"1"]
                ) {

                // It's a match, add the story
                [self.favList addObject:myArrayElement];

                // EXIT THE INNER LOOP NOW WE HAVE A MATCH
            }
        } // prefsDictionary End if
    } // End myIssueElement for
} // End myArrayElement for

除非有人有一个很棒的想法......

Answer 1

如果您只是想确保查看每个数组中的所有值，我实际上会站在 nielsbot 一边。只需插入

MAX(arrayA.count, MAX(arrayB.count, arrayC.count))

for 循环参数即可覆盖它。

for( int i=0; i < MAX(arrayA.count, MAX(arrayB.count, arrayC.count)); i++ ) {
    // Blah Blah Blah
}

MAX() 返回两个值中的较大者，使您可以轻松选出最高计数。从您的示例代码来看，您似乎实际上并不需要最长的数组，而只需要最高的计数。

Answer 2

如果您想做的只是找出哪个数组具有最高计数，这将是我会采取的方法：

NSArray *largestArray = arrayA;
if ([largestArray count] < [arrayB count]) {
    largestArray = arrayB;
}
if ([largestArray count] < [arrayC count]) {
    largestArray = arrayC;
}

如果有更多数组，这不是最佳方法，但对于只有三个数组，它应该做美好的。这应该每次都返回最大的数组