Hash quiz game system development how to develop hash quiz game system development (multiple cases)

　　 A hash table is a key - value (key-indexed) Structure of stored data , We just input the value to be searched key, You can find the corresponding value .

　　 The idea of hash is very simple , If all keys are integers , Then you can use a simple unordered array to achieve ： Key as index , Value is its corresponding value , In this way, you can quickly access the value of any key . This is for simple keys , We extend it to keys that can handle more complex types .

　　How is hash applied in blockchain?

　　In the blockchain,each block has the hash value of the previous block,which is called the parent block of the current block.Since each block has the hash value of the previous block,when modifying any data of the current block,the hash value of the block will change,which will have an impact on the previous block,because it contains the address of the previous block.

　　For example,there are currently two blocks,one is the current block,and the other is the parent block.The current block has the address of the parent block.If you need to modify the data of the current block,you need to modify the parent blockchain.It is easier to modify data if there are only two blocks,but in fact,there are many blocks on the blockchain.

　　 There are two steps to using hash lookup ：

　　1. Use the hash function to convert the key to the index of the array . In an ideal situation , Different keys will be converted to different index values , But in some cases we need to deal with multiple keys being hashed to the same index value . So the second step of hash lookup is to handle conflicts

　　2. Handle hash collision conflicts . There are many ways to handle hash collision conflicts , The zipper method and linear detection method will be introduced later in this paper .

　　 Hash table is a classic example of making a trade-off between time and space . If there is no memory limit , Then you can directly use the key as the index of the array . Then all the search time complexity is O(1); If there is no time limit , Then we can use unordered arrays and look them up in order , This requires very little memory . Hashtable uses a moderate amount of time and space to find a balance between these two extremes . Just adjust the hash function algorithm to make the trade-off between time and space .

　　 stay Hash In the table , There is a definite relationship between the position of the record in the table and its keywords . In this way, we can know the position of the keyword in the table in advance , To find records directly by subscript . send ASL Approach and 0.

　　1) Hash (Hash) A function is a map , namely ： Map a set of keywords to an address set , Its settings are flexible , As long as the size of this address set does not exceed the allowable range ;

　　2) Because the hash function is a compressed image , therefore , In general , Easy to produce “ Conflict ” The phenomenon , namely ：key1！=key2, and f(key1)=f(key2).

　　3). Conflicts can only be minimized but not completely avoided , This is because the keyword set is usually large , Its elements include all possible keywords , The elements of the address set are only the address values in the hash table

　　 In constructing this special “ Lookup table ” when , In addition to choosing one “ good ”( As little conflict as possible ) Outside the hash function of ; We still need to find one “ Handling conflicts ” Methods .

　　Compared with traditional notarization and other third-party deposit forms,blockchain deposit has the following advantages:

　　1.It cannot be tampered with.Blockchain technology can package a certain range of electronic data in a recognized way,then"Encrypt and calculate",get a"check value",and form a"block".All the information in this"block"will be included in the next"block".As the number of blocks increases gradually,the blocks become a chain connected end to end.Because the data changes of each block must follow the algorithm rules within the blockchain,and the update of the data on the chain needs to reach an agreement with all other blocks,the more blocks the chain contains,the less the probability of being modified,until it can be ignored,In this way,after being fixed and saved by blockchain and its extension technology,electronic data has the property of anti-counterfeiting.

　　2.Prevent loss.Blockchain certificate deposit has the advantage of anti loss,which is derived from the tamper resistant nature of blockchain.Each block will store data completely according to the chain structure.As long as not all blocks are damaged,the information will not be lost.

　　3.Traceability.Since the blockchain is arranged in sequence according to the time sequence of each block,users can trace back to the source of the information according to the timestamp information on the blockchain,and the authenticity and accuracy of the information can be guaranteed.

　　4.Efficient and convenient.Compared with traditional electronic data collection,it has the disadvantages of high fixed cost and low efficiency.Blockchain deposit can technically fix evidence,reduce the cost of proof and improve the efficiency of judicial work.At the same time,blockchain certificate deposit can gradually reduce the links of third-party authentication,authentication or notarization in the review process,thereby reducing the investment of judicial review time and energy.