LeetCode 1346 | Check If N and Its Double Exist | TreeSet | Java

Questions in English: https://docs.google.com/spreadsheets/d/1QNSEok-WD4LCPTrZlqq5VVTX0NbXQf27WUjkGi3aBu0/edit?usp=sharing Questions in Mandarin: https://docs.google.com/spreadsheets/d/1aMCmSLucm7I_7BIRz1SqHy8c1D9h_6M8XAkrqWXSy8Y/edit?usp=sharing