Equations are given in the format A / B = k, where A and B are variables represented as strings, and k is a real number (floating point number). Given some queries, return the answers. If the answer does not exist, return -1.0.
Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times.
Given a digit string, return all possible letter combinations that the number could represent.
A mapping of digit to letters (just like on the telephone buttons) is given below.
Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.
In the computer world, use restricted resource you have to generate maximum benefit is what we always want to pursue.
For now, suppose you are a dominator of m 0s and n 1s respectively. On the other hand, there is an array with strings consisting of only 0s and 1s.
Remember the story of Little Match Girl? By now, you know exactly what matchsticks the little match girl has, please find out a way you can make one square by using up all those matchsticks. You should not break any stick, but you can link them up, and each matchstick must be used exactly one time.
今年春天的时候，我一直在寻找令自己满意的实习机会：一方面是想在找实习的过程中查漏补缺，提高自己；另一方面是给自己漫长的暑假，找一件有意义的事情来干。当然还有导火索——身边的同学不知道为啥，突然就一个个地接到了BAT各家公司的电话和通知，自己不禁也想试一试；其实找实习，很大程度上也是一种从众心理。
Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly updated) of the BST.