You may know that an unbounded wildcard Set<?> can hold elements of any type, and a raw type Set can also hold elements of any type. What is the difference between them?

# Month: December 2013

## LeetCode – Reorder List (Java)

Given a singly linked list L: L0â†’L1â†’ … â†’Ln-1â†’Ln, reorder it to: L0â†’Lnâ†’L1â†’Ln-1â†’L2â†’Ln-2â†’… For example, given {1,2,3,4}, reorder it to {1,4,2,3}. You must do this in-place without altering the nodes’ values. Java Solution Because the problem requires “in-place” operations, we can only change their pointers, not creating a new list. This problem can be solved … Read more

## Leetcode – Longest Palindromic Substring (Java)

Finding the longest palindromic substring is a classic problem of coding interview. This post summarizes 3 different solutions for this problem. 1. Dynamic Programming Let s be the input string, i and j are two indices of the string. Define a 2-dimension array “table” and let table[i][j] denote whether a substring from i to j … Read more