摘要：
Given the array arr of positive integers and the array queries where queries[i] = [Li, Ri], for each query i compute the XOR of elements from Li to Ri 阅读全文
摘要：
Given a string s formed by digits ('0' - '9') and '#' . We want to map s to English lowercase characters as follows: Characters ('a' to 'i') are repre 阅读全文