摘要： 题目如下： With respect to a given puzzle string, a word is valid if both the following conditions are satisfied: word contains the first letter of puzzle. 阅读全文

摘要： 题目如下： Given a string s, we make queries on substrings of s. For each query queries[i] = [left, right, k], we may rearrange the substring s[left], ..., 阅读全文

摘要： 题目如下： Return the number of permutations of 1 to n so that prime numbers are at prime indices (1-indexed.) (Recall that an integer is prime if and only 阅读全文