Problem description:

The string “PAYPALISHIRING” is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

1
2
3

P   A   H   N
A P L S I I G
Y   I   R

Problem description:

Given a 2D board and a list of words from the dictionary, find all words in the board.

4-5 Atomic Transaction

Problem description:

A website domain like “discuss.leetcode.com” consists of various subdomains. At the top level, we have “com”, at the next level, we have “leetcode.com”, and at the lowest level, “discuss.leetcode.com”. When we visit a domain like “discuss.leetcode.com”, we will also visit the parent domains “leetcode.com” and “com” implicitly.

Problem description:

Design a data structure that supports all following operations in average O(1) time.

Problem description:

You’re given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in S is a type of stone you have. You want to know how many of the stones you have are also jewels.

Problem description:

Given a non-empty list of words, return the k most frequent elements.

Problem description:

Given a binary tree, return the zigzag level order traversal of its nodes’ values. (ie, from left to right, then right to left for the next level and alternate between).

Problem description:

In an array A of 0s and 1s, how many non-empty subarrays have sum S?

Oct 26th:
1, 2,
3. Longest Substring Without Repeating Characters, use a left variable to denote the start
5. Longest Palindromic Substring