## String and StringBuffer

Introduce string and string buffer

Introduce string and string buffer

Given two binary strings, return their sum (also a binary string).

Get the nth sequence of the count-and-say sequences.

Given a string s consists of upper/lower-case alphabets and empty space characters ‘ ‘, return the length of last word in the string.

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

Compare two version numbers version1 and version2.

Find the longest common prefix string amongst an array of strings.

Given a list of non negative integers, arrange them such that they form the largest number.

Given a sorted integer array without duplicates, return the summary of its ranges.

Convert a string to the ZigZag pattern

Implement atoi to convert a string to an integer.

Given a string S, find the longest palindromic substring in S

Given two strings s and t, write a function to determine if t is an anagram of s.

Given a pattern and a string str, find if str follows the same pattern.

Bulls and Cows is an interesting problem that could be solved by hash table in an interesting way.

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

Additive number is a string whose digits can form additive sequence...