You are given coins of different denominations and a total amount of money amount. Write a function to compute the fewest number of coins that you need to make up that

Given a string s consisting only of letters ‘a’ and ‘b’. In a single step you can remove one palindromic subsequence from s.

Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.

Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Singly-Linked List

9. Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

7. Given a 32-bit signed integer, reverse digits of an integer.

1. Given an array of integers, return indices of the two numbers such that they add up to a specific target.