摘要：
Given a nested list of integers, return the sum of all integers in the list weighted by their depth. Each element is either an integer, or a list -- w 阅读全文
摘要：
Implement an iterator to flatten a 2d vector. Example: Input: 2d vector = [ [1,2], [3], [4,5,6] ] Output: [1,2,3,4,5,6] Explanation: By calling next r 阅读全文