| #| Name| Solution| Youtube|

|:----:|-----------------------------------------------------------------------------------------------------------------------------------------------------------|:------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------:|:---------------------------------------------------------------------------------------------------------------------------------:|

| 1|[Two Sum](https://leetcode.com/problems/two-sum/)|[](src/TwoSum.java)[](python/two_sum.py)|[](https://youtu.be/9wSL_7NN-A8)[](https://youtu.be/N5FXCTg0TDE)|

| 1|[Two Sum](https://leetcode.com/problems/two-sum)|[](src/TwoSum.java)[](python/two_sum.py)|[](https://youtu.be/9wSL_7NN-A8)[](https://youtu.be/N5FXCTg0TDE)|

| 2|[Add Two Numbers](https://leetcode.com/problems/add-two-numbers)|[](src/AddTwoNumbers.java)||

| 3|[Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters)|[](src/LongestSubstringWithoutRepeatingCharacters.java)||

| 5|[Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring)|[](src/LongestPalindromicSubstring.java)||

| 89|[Gray Code](https://leetcode.com/problems/gray-code)|[](src/GrayCode.java)||

| 90|[Subsets II](https://leetcode.com/problems/subsets-ii)|[](src/SubsetsII.java)||

| 91|[Decode Ways](https://leetcode.com/problems/decode-ways)|[](src/DecodeWays.java)||

| 92|[Reverse Lined](https://leetcode.com/problems/decode-ways)|[](src/DecodeWays.java)||

| 94|[Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/)|[](src/BinaryTreeInorderTraversal.java)[](python/binary_tree_inorder_traversal.py)||

| 100|[Same Tree](https://leetcode.com/problems/same-tree)|[](src/SameTree.java)[](python/same_tree.py)||

| 101|[Symmetric Tree](https://leetcode.com/problems/symmetric-tree)|[](src/SymmetricTree.java)[](python/symmetric_tree.py)||

}

}

publicstaticvoidmain(String[]args) {

ListNodehead =newListNode(1);

head.next =newListNode(2);

head.next.next =newListNode(3);

head.next.next.next =newListNode(4);

head.next.next.next.next =newListNode(5);

System.out.println(reverseBetween(head,2,4));

}

publicListNodereverseBetween(ListNodehead,intm,intn) {

if (head ==null ||m ==n) {

returnhead;

}

publicstaticListNodereverseBetween(ListNodehead,intleftVal,intrightVal) {

if (leftVal ==rightVal)returnhead;

ListNodecur =head,prev =null;

while (m >1) {

prev =cur;

cur =cur.next;

m--;

n--;

}

ListNodesentinelHead =newListNode(-1000);

sentinelHead.next =head;

ListNodebeforeLeft =getNodeBefore(sentinelHead,leftVal);

System.out.println(beforeLeft.val);

ListNodeleft =beforeLeft.next;

ListNodea =beforeLeft.next,b =a.next,c =b.next;

ListNodecon =prev,tail =cur;

while (c !=null &&b.val !=rightVal) {

a.next =null;

b.next =a;

a =b;

b =c;

c =c.next;

ListNodethird =null;

while (n >0) {

third =cur.next;

cur.next =prev;

prev =cur;

cur =third;

n--;

}

b.next =a;

beforeLeft.next =b;

left.next =c;

returnsentinelHead.next;

}

privatestaticListNodegetNodeBefore(ListNodehead,intvalue) {

while (head !=null &&head.next !=null &&head.next.val !=value) {

head =head.next;

if (con !=null) {

con.next =prev;

}else {

head =prev;

}

tail.next =cur;

returnhead;

}

}