如何生成非重复随机数 [英] How to generate non repeating random number

问题描述

我试图在数组中随机化数字。我可以这样做使用 arc4random（）％[索引计数]

I am trying to randomize numbers in an array. I am able to do that using arc4random() % [indexes count]

我的问题是 - 由20个项目组成，每次数组shuffle，在一批5中，不同的数字应该出现。示例：

My problem is - If an array consists of 20 items, every time the array shuffles, in a batch of 5, different number should appear. Example :

第一个shuffle：1,4,2,5,6。

first shuffle: 1,4,2,5,6.

12,9,15,3

second shuffle: 7,12,9,15,3

-(IBAction)randomNumbers:(UIButton *)sender
{
    int length = 10; // int length = [yourArray count];

    NSMutableArray *indexes = [[NSMutableArray alloc] initWithCapacity:length];
    for (int i=0; i<5; i++)
        [indexes addObject:[NSNumber numberWithInt:i]];

    NSMutableArray *shuffle = [[NSMutableArray alloc] initWithCapacity:length];

    while ([indexes count])
    {
        int index = arc4random() % [indexes count];
        [shuffle addObject:[indexes objectAtIndex:index]];
        [indexes removeObjectAtIndex:index];
    }

    //    for (int i=0; i<[shuffle count]; i++)
    NSLog(@"%@", [shuffle description]);
}

推荐答案

请仔细检查此代码

将此属性设为

@synthesize alreadyGeneratedNumbers;

在您的.m中添加这些方法

Add these methods in your .m

-(int)generateRandomNumber{

    int TOTAL_NUMBER=20;

    int low_bound = 0;
    int high_bound = TOTAL_NUMBER;
    int width = high_bound - low_bound;
    int randomNumber = low_bound + arc4random() % width;

    return randomNumber;
}


-(IBAction)randomNumbers:(UIButton *)sender
{

    NSMutableArray *shuffle = [[NSMutableArray alloc] initWithCapacity:5];

    BOOL contains=YES;
    while ([shuffle count]<5) {
        NSNumber *generatedNumber=[NSNumber numberWithInt:[self generateRandomNumber]];
        //NSLog(@"->%@",generatedNumber);

        if (![alreadyGeneratedNumbers containsObject:generatedNumber]) {
            [shuffle addObject:generatedNumber];
            contains=NO;
            [alreadyGeneratedNumbers addObject:generatedNumber];
        }
    }

    NSLog(@"shuffle %@",shuffle);
    NSLog(@"Next Batch");


    if ([alreadyGeneratedNumbers count] >= TOTAL_NUMBER) {
        NSLog(@"\nGame over, Want to play once again?");//or similar kind of thing.
        [alreadyGeneratedNumbers removeAllObjects];
    }


}

你需要一些变化，例如

它会给你正确的价值，但如果用户第五次按下怎么办？

it will give you correct value, but what if user pressed 5th time?

您已经选择了20个数字中的4个5个数字，第6次，它将循环搜索下一组数字，并将变为无限。

out of 20 numbers you already picked 4 sets of 5 number, on on 6th time it will be in loop to search for next set of numbers and will become infinite.

所以你可以做的是，保持随机播放的轨道，一旦达到极限，即20/5 = 4禁用随机按钮。

So what you can do is, keep the track of shuffle and once it reaches the limit i.e, 20/5=4 disable the random button.

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