Tiger's leetcode solution

Q: Given an integer  n , return  the number of prime numbers that are strictly less than   n .   Example 1: Input: n = 10 Output: 4 Expla...

Q: Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starti...

Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive. Example 1: In...

Given an  m x n  2D binary grid  grid  which represents a map of  '1' s (land) and  '0' s (water), return  the number of isl...

Given the  root  of a binary tree, imagine yourself standing on the  right side  of it, return  the values of the nodes you can see ordered ...