摘要：
Given a string S of '(' and ')' parentheses, we add the minimum number of parentheses ( '(' or ')', and in any positions ) so that the resulting paren 阅读全文
摘要：
Given an array A of integers, we must modify the array in the following way: we choose an i and replace A[i] with -A[i], and we repeat this process K 阅读全文
摘要：
Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may comple 阅读全文
摘要：
We are given an array A of N lowercase letter strings, all of the same length. Now, we may choose any set of deletion indices, and for each string, we 阅读全文
摘要：
Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction 阅读全文