Travel code is the code of communication big data travel card, which is also equivalent to health code. China Institute of Information and Communication, together with China Telecom, China Mobile and China Unicom, used mobile phones to receive data, which was obtained through the location of the base station where the users' mobile phones were located, providing free inquiry service for the 654.38+06 billion mobile phone users nationwide. Mobile phone users can query all the city information they have been to before 654.38+04 days through this service.
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Run-length coding can be divided into fixed-length run-length coding and variable-length run-length coding. Fixed-length run-length coding refers to a fixed number of binary digits used in the coding run. If the number of consecutive equal gray levels exceeds the maximum value that can be represented by a fixed binary number, the next round of run-length coding is performed. Variable-length run-length coding refers to the use of binary digits with different digits for different run ranges, and flag bits need to be added to represent the binary digits used.
Refer to the above content: Baidu Encyclopedia-Run-length Coding