LeetCode Array 1. Two Sum，Easy 121. Best Time to Buy and Sell Stock，Easy 217. Contains Duplicate，Easy Linked List 21. Merge Two Sorted Lists，Easy String 9. Palindrome Number，Easy 2243. Calculate Digit Sum of a String，Easy Tree 94. Binary Tree Inorder Traversal，Easy 100. Same Tree，Easy 104. Maximum Depth of Binary Tree，Easy 144. Binary Tree Preorder Traversal，Easy 145. Binary Tree Postorder Traversal，Easy 參考資源 Blind 75 LeetCode Questions LeetCode Notion labuladong 的算法小抄