You are given a string s containing “1”s and “0”s. Return the number of substrings that contain only “1”s. Mod the result by 10 ** 9 + 7. Constraints …
Teaching Kids Programming: Videos on Data Structures and Algorithms Given the root to a binary tree root, return whether it is symmetric. Constraints n ≤ 100,000 where n is …
Given a string digits containing 2 to 9 inclusive, return in sorted lexicographic order all possible strings it could represent when mapping to letters on a phone dialpad. These …
Teaching Kids Programming: Videos on Data Structures and Algorithms This problem was inspired by this original tweet by Max Howell: Google: 90% of our engineers use the software you …
You are given a list of integers nums. Return the number of pairs i < j such that nums = nums. Constraints 0 ≤ n ≤ 100,000 where n …
Teaching Kids Programming: Videos on Data Structures and Algorithms Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following …