Robina Li

Given a string s, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smallest in lexicographical order among all...

In English, we have a concept called root, which can be followed by some other word to form another longer word. Let’s call this word successor. For example, when the...

Given an integer array nums, return the length of the longest strictly increasing subsequence.

Given a circular integer array nums (i.e., the next element of nums[nums.length - 1] is nums[0]), return the next greater number for every element in nums.

You are given an integer array nums.

Given the integers zero, one, low, and high, we can construct a string by starting with an empty string, and then at each step perform either of the following:

We are given hours, a list of the number of hours worked per day for a given employee.

You are given an integer array nums and an integer target.

Given a string s, find the length of the longest substring without repeating characters.

Write an efficient algorithm that searches for a value target in an m x n integer matrix. This matrix has the following properties: