MasterMind scoring algorithm in Objective C

I'm looking for an elegant way to compute the score of a guess in the MasterMind game in Objective C, based on this article already on stackoverflow:

MasterMind scoring algorithm in C# using LIN开发者_JAVA百科Q

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I assume you can do this in 'not so elegant' imperative way with NSArray and NSSet.

For functional approach used in LINQ solution you can either

1) google for some Objective-C functional lib - http://www.google.com/search?q=functional+programming+objective-c

or

2) implement required functions - Intersect, Zip, Count, Sum.

• Intersect(a1, a2). Make sets from your arrays and make intersection with objectsPassingTest:.

• Zip(block, a1, a2). Iterate max(a1.count, a2.count) and push into answer array result of calling block on corresponding array elements.

• Count(predicate, array) is Sum((x -> predicate(x) ? 1 : 0), array)

• Sum(block, array) is Foldl((x, sum -> sum + block(x)), 0, array)

• Foldl(block, init, array) is id result = init; for (id obj in array) { result = block(result, obj); }

I believe no matter what approach you select result will be ugly as hell. Objective-C just isn't that kind of language.

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For now I've come up with this (well, it's actually C but you can easily rewrite it using NSArray and isEqual)

int secret[] = { 1, 2, 3, 1 };
int guess[]  = { 1, 1, 2, 2 };
int white = 0, black = 0;
for(int i=0; i<4; ++i) {
    if( secret[i] == guess[i] ) {
        secret[i] = 0;
        ++white;
        continue;
    }
    for(int j=0; j<4; ++j) {
        if( secret[j] == guess[i] ) {
            secret[j] = 0;
            ++black;
            break;
        }
    }
}

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An answer inspired by Max's answer, but updated to deal with a case where (in my opinion) it provides the wrong answer:

int secret[] = { 1, 1, 2, 3 };
int guess[]  = { 4, 1, 5, 1 };
int white = 0, black = 0;
for(int i=0; i<4; ++i) {
    if( secret[i] == guess[i] ) {
        secret[i] = 0;
        ++white;
        continue;
    }
    for(int j=0; j<4; ++j) {
        if( secret[j] == guess[i] ) {
            if ( secret[j] == guess[j] ) {
                ++white;
            } else {
                ++black;
            }
            secret[j] = 0;
            break;
        }
    }
}