摘要：
B. Diverse Substrings A non-empty digit string is diverse if the number of occurrences of each character in it doesn't exceed the number of distinct c 阅读全文
摘要：
Maximum Number of Non-overlapping Palindrome Substrings You are given a string s and a positive integer k . Select a set of non-overlapping substrings 阅读全文
摘要：
Minimum Number of Operations to Sort a Binary Tree by Level You are given the root of a binary tree with unique values. In one operation, you can choo 阅读全文