iOS开发 ☞ 组合算法

最新推荐文章于 2020-08-27 21:52:02 发布

转载最新推荐文章于 2020-08-27 21:52:02 发布 · 1.6k 阅读

文章标签：

#算法 #组合 #组合数 #排列组合

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本文介绍了一种使用 Objective-C 实现的组合算法，该算法能够从给定数组中选择特定数量的元素进行组合，并返回所有可能的组合结果。文章通过具体代码展示了如何通过遍历和状态改变的方式生成这些组合。

转自：http://www.cocoachina.com/bbs/read.php?tid=113856

- (NSMutableArray *)zuHeSuanFa:(NSMutableArray *)array chooseCount:(int)m
{     
    int n = [array count];

    if (m > n)
    {
        return nil;
    }

    NSLog(@"从1到%d中取%d个数的组合。。。",n,m);

    NSMutableArray *allChooseArray = [[NSMutableArray alloc] init];
    NSMutableArray *retArray = [array copy];

    // (1,1,1,0,0)
    for(int i=0;i < n;i++)
    {
        if (i < m)
        {
            [array replaceObjectAtIndex:i withObject:@"1"];
        }
        else 
        {
            [array replaceObjectAtIndex:i withObject:@"0"];
        }
    }

    NSMutableArray *firstArray = [[NSMutableArray alloc] init];

    for(int i=0; i<n; i++)
    {
        if ([[array objectAtIndex:i] intValue] == 1) 
        {
//            [firstArray addObject:[NSString stringWithFormat:@"%d",i+1]];
            [firstArray addObject:[retArray objectAtIndex:i]];
        }
    }

    [allChooseArray addObject:firstArray];
//    [firstArray release];

    int count = 0;
    for(int i = 0; i < n-1; i++)
    {
        if ([[array objectAtIndex:i] intValue] == 1 && [[array objectAtIndex:(i + 1)] intValue] == 0)
        {
            [array replaceObjectAtIndex:i withObject:@"0"];
            [array replaceObjectAtIndex:(i + 1) withObject:@"1"];

            for (int k = 0; k < i; k++)
            {
                if ([[array objectAtIndex:k] intValue] == 1)
                {
                    count ++;
                }
            }
            if (count > 0)
            {
                for (int k = 0; k < i; k++)
                {
                    if (k < count)
                    {
                        [array replaceObjectAtIndex:k withObject:@"1"];
                    }
                    else 
                    {
                        [array replaceObjectAtIndex:k withObject:@"0"];
                    }
                }
            }

            NSMutableArray *middleArray = [[NSMutableArray alloc] init];

            for (int k = 0; k < n; k++)
            {
                if ([[array objectAtIndex:k] intValue] == 1)
                {
//                    [middleArray addObject:[NSString stringWithFormat:@"%d",k + 1]];
                    [middleArray addObject:[retArray objectAtIndex:k]];
                }
            }

            [allChooseArray addObject:middleArray];
//            [middleArray release];

            i = -1;
            count = 0;
        }
    }

    return allChooseArray;
}