* Update hash_collision.md
a detailed description of the conditions for converting a linked list into a red-black tree is as follows.
```java
final void treeifyBin(Node<K,V>[] tab, int hash) {
int n, index; Node<K,V> e;
if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)
}
```
* Update hash_collision.md
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Co-authored-by: Yudong Jin <krahets@163.com>