摘要：
Is there a tree?Time Limit : 2000/1000ms (Java/Other)Memory Limit : 65536/32768K (Java/Other)Total Submission(s) : 19Accepted Submission(s) : 3Font:Times New Roman|Verdana|GeorgiaFont Size:←→Problem DescriptionA tree is a well-known data structure that is either empty (null, void, nothing) or is a s 阅读全文