Search a 2D Matrix II Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted in ascending from left to right. Integers in each column are sorted in ascending from top to bottom. […]

Strobogrammatic Number III A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to count the total strobogrammatic numbers that exist in the range of low <= num <= high. For example, Given low = “50”, high = “100”, […]

Group Shifted Strings Given a string, we can “shift” each of its letter to its successive letter, for example: “abc” -> “bcd”. We can keep “shifting” which forms the sequence: “abc” -> “bcd” -> … -> “xyz” Given a list of strings which contains only lowercase alphabets, group all strings […]

Different Ways to Add Parentheses Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid operators are+, – and *. Example 1 Input: “2-1-1”. ((2-1)-1) = 0 (2-(1-1)) = 2 Output: [0, 2] Example 2 […]