## 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].