▍1. search-the-number
用于求三组数,每组数的各个位都不相同。第二组数为第一组的2倍,第3组数为第一组的3倍(Is used to find the number of three, the number of the bits in each group are different. The second number of groups for the first group of two times the number of the third group of three times the first group)