Ask a question about the algorithm.

ask a question, for example, in the box in the picture, I randomly point to a number in the graph, then the adjacent squares of this number are also clicked, and then the adjacent squares of these adjacent squares are also clicked. Recursively (for example, when I click 1, 1.1-1.9 is lit, and then the neighbors of 1 are all lit, the neighbors of 2.1-2.4 are also lit), what data structure and algorithm are used to implement it?
Oct.15,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1eb0dfe-2313.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1eb0dfe-2313.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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