(Some people fall in love, some people drive to see the sea at night, and some people can't solve the first problem of LeetCode. There is a long way to go to do the questions, and LeetCode is an insurmountable hurdle. Many people get stuck on the first question—not because they don’t know how to write the questions, but because they don’t know how to write and pass them correctly. LeetCode's programming idea, in layman's terms, is to input data on the server side, and return the corresponding output value through the processing of the written method (function in C language). All the programmer has to do is write a method/function to handle the requirements of the topic.)