LeetCode #508 Most Frequent Subtree Sum 出现次数最多的子树元素和
508MostFrequentSubtreeSum出现次数最多的子树元素和Description:Giventherootofatree,youareaskedtofindthemostfrequentsubtreesum.Thesubtreesumofanodeisdefinedasthesumofallthenodevaluesformedbythesubtreerootedatthatnod