注：
一般方法的第一种解法为最容易想到的解法

方法 +（functionName_approach_number）为该问题的优化解或最优解

eg:
Generally speaking, the first solution of the method is the easiest one to think of

Method plus (functionName_approach_number) is a better optimal or the best optimal solution for the problem

    |-- src
    |   |-- main
    |   |   |-- java
    |   |   |   |-- com
    |   |   |       |-- lonuslan
    |   |   |           |-- dailyleetcode
    |   |   |               |-- chapter1
    |   |   |               |   |-- AddTwoNumbers.java
    |   |   |               |   |-- LongestSubstringWithoutRepeatingCharacters.java
    |   |   |               |   |-- MedianOfTwoSortedArrays.java
    |   |   |               |   |-- TwoSum.java
    |   |   |               |-- chapter2
    |   |   |               |   |-- ContainerWithMostWater.java
    |   |   |               |   |-- IntegerToRoman.java
    |   |   |               |   |-- LongestPalindromicSubstring.java
    |   |   |               |   |-- PalindromeNumber.java
    |   |   |               |   |-- RegularExpressionMatching.java
    |   |   |               |   |-- ReverseInteger.java
    |   |   |               |   |-- StringToIntegerAtoi.java
    |   |   |               |   |-- ZigzagConversion.java
    |   |   |               |   |-- chapter2easy
    |   |   |               |   |   |-- LongestCommonPrefix.java
    |   |   |               |   |   |-- RomanToInteger.java
    |   |   |               |   |   |-- ValidParentheses.java
    |   |   |               |   |-- chapter2hard
    |   |   |               |   |-- chapter2medium
    |   |   |               |       |-- LetterCombinationsOfAPhoneNumber.java
    |   |   |               |-- chapter3
    |   |   |               |   |-- class1.java
    |   |   |               |   |-- chapter3easy
    |   |   |               |   |   |-- ImplementStrstr.java
    |   |   |               |   |-- chapter3hard
    |   |   |               |   |-- chapter3medium
    |   |   |               |       |-- DivideTwoIntegers.java
    |   |   |               |-- entity
    |   |   |               |   |-- ListNode.java
    |   |   |               |   |-- Result.java
    |   |   |               |-- template
    |   |   |               |   |-- TemplateProblemDescription.java
    |   |   |               |-- utils
    |   |   |-- resources
    |   |       |-- properties.yml
    |   |-- test
    |       |-- java
    |           |-- com
    |               |-- lonuslan
    |                   |-- dailyleetcode
    |                       |-- chapter1
    |                       |   |-- AddTNTest.java
    |                       |   |-- LongestSubWithoutRepCharTest.java
    |                       |   |-- MedianOfTwoSortedArraysTest.java
    |                       |   |-- TwoSumTest.java
    |                       |-- chapter2
    |                       |   |-- ContainerWithMostWaterTest.java
    |                       |   |-- IntegerToRomanTest.java
    |                       |   |-- LongestPalindromicSunstringTest.java
    |                       |   |-- PalindromeNumberTest.java
    |                       |   |-- RegularExpressionMatchingTest.java
    |                       |   |-- ReverseIntegerTest.java
    |                       |   |-- StringToIntegerAtoiTest.java
    |                       |   |-- ZigzagConversionTest.java
    |                       |   |-- chapter2easy
    |                       |   |   |-- LongestCommonPrefixTest.java
    |                       |   |   |-- RomanToIntegerTest.java
    |                       |   |   |-- ValidParenthesesTest.java
    |                       |   |-- chapter2medium
    |                       |       |-- LetterCombinationsOfAPhoneNumberTest.java
    |                       |-- chapter3
    |                           |-- chapter3easy
    |                           |   |-- ImplementStrstrTest.java
    |                           |-- chapter3medium
    |                               |-- DivideTwoIntegersTest.java