[Solved] Given an integer n, return a string with n characters such that each character in such string occurs an odd number of times. The returned string must contain only lowercase English letters. If there are multiples valid strings, return any of them.
[Solved] Given the array nums, for each nums[i] find out how many numbers in the array are smaller than it. That is, for each nums[i] you have to count the number of valid j’s such that j != i and nums[j] < nums[i]. Return the answer in an array.
[Solved] Given a m x n matrix grid which is sorted in non-increasing order both row-wise and column-wise, return the number of negative numbers in grid.
[Solved] Given an integer num, return the number of steps to reduce it to zero.
[Solved] You are given an m x n binary matrix mat of 1’s (representing soldiers) and 0’s (representing civilians). The soldiers are positioned in front of the civilians. That is, all the 1’s will appear to the left of all the 0’s in each row.
[Solved] You are given a string s consisting only of letters ‘a’ and ‘b’. In a single step you can remove one palindromic subsequence from s. Return the minimum number of steps to make the given string empty.
[Solved] Given a binary tree root and an integer target, delete all the leaf nodes with value target.
[Solved] You are given a positive integer num consisting only of digits 6 and 9. Return the maximum number you can get by changing at most one digit (6 becomes 9, and 9 becomes 6).
[Solved] No-Zero integer is a positive integer that does not contain any 0 in its decimal representation. Given an integer n, return a list of two integers [A, B] where: