He is a linked list, which is very inconvenient.
Over time is too long.
How to change it into a hash table?
do you know? Similarly, can you help me?thanks.

--------------------------------

Of course, I hope it becomes a "map" structure.

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or，tell me 5.050*10^8 tick， need 1ghz cpu what time？

I am sorry.Although I use Google Translate.But obviously not easy.
I will use the programmer's common language.code.

array[1000]{1,2,3...};

for(int i = 0;i < 1000;i++)
{
    if(array[i] == x){
    //something
    }
}

Like this, if the array is 10000? 100000?
It takes too much time.

@Edgar Reynaldo

Projectile collision.This is the structure of my code.
But obviously, assuming I have 1000 objects and 1000 bullets, I need to count 1000 * 1000 times.

Oh my god.
--------------------
I need a better algorithm.
But I can not find the literature at Baidu.
In Google, I can not find the location.Because it is English.

If you can, can you give me some information?

@LennyLen

I lack relevant knowledge, need some literature.
On the Chinese search engine, only some useless crap.
Or, you tell me, what books have such knowledge.

Thanks！