## LeetCode problem 424 Longest Repeating Character Replacement(Java)

Given a string that consists of only uppercase English letters, you can replace any letter in the string with another letter at most k times. Find the length of a longest substring containing all repeating letters you can get after performing the above operations.

Note:
Both the string’s length and k will not exceed 104.

Example 1:

Input: s = “ABAB”, k = 2
Output: 4
Explanation: Replace the two ‘A’s with two ‘B’s or vice versa.

Example 2:

Input: s = “AABABBA”, k = 1
Output: 4
Explanation: Replace the one ‘A’ in the middle with ‘B’ and form “AABBBBA”. The substring “BBBB” has the longest repeating letters, which is 4.

## LeetCode Problem 30 Substring with Concatenation of All Words (Java)

You are given a string, s, and a list of words, words, that are all of the same lengths. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and without any intervening characters.

Example 1:

Input: s = “barfoothefoobarman”, words = [“foo”,”bar”]
Output: `[0,9]`
Explanation: Substrings starting at index 0 and 9 are “barfoor” and “foobar” respectively. The output order does not matter, returning [9,0] is fine too.

## LeetCode 3. Longest Substring Without Repeating Characters (Java)

Given a string, find the length of the longest substring without repeating characters.

Example 1:
Input: “abcabcbb”
Output: 3
Explanation: The answer is `"abc"`, with the length of 3.

Example 2:
Input: “bbbbb”
Output: 1
Explanation: The answer is `"b"`, with the length of 1.

Example 3:
Input: “pwwkew”
Output: 3
Explanation: The answer is `"wke"`, with the length of 3.
Note that the answer must be a substring, `"pwke"` is a subsequence and not a substring.

## Leetcode 2 Add Two Numbers (Java)

Medium

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contains a single digit. Add the two numbers and return it as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example:
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

## Leetcode 1. Two Sum (Java)

Source Url: https://leetcode.com/problems/two-sum/

Easy

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

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1].

## Where is Sri Lanka?

Sri Lanka officially the Democratic Socialist Republic of Sri Lanka is an island country in South Asia, located in the Indian Ocean to the southwest of the Bay of Bengal and the southeast of the Arabian Sea. The island is geographically separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait. The legislative capital, Sri Jayawardenepura Kotte, is a suburb of the commercial capital and largest city, Colombo.

## 8 Reasons about I love living in Shanghai

Shanghai is my most favorite city in China. Since 2010, I moved to Shanghai from Beijing. I have lived in Shanghai for eight years. After these eight years, I think Shanghai is the best city in China.

And there are 8 reasons: