String is a special class in Java and substring() method of String class is one of the widely used methods of String class. It is used to extract part of a string and has two overloaded variants: ...

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n). 1. If there is no such window in S that covers all characters in T, return ...

Given "abcabcbb", the answer is "abc", which the length is 3. Given "bbbbb", the answer is "b", with the length of 1. Given "pwwkew", the answer is "wke", with the ...