NG转码小白刷题打卡

7/25 Mon: (Day 58, total new +0 = 391 + (24), redo 0 old) 今日努力不能，躺平
- redo old:
- 34. Find First and Last Position of Element in Sorted Array

7/26 Tue: (Day 59, total new + 7 = 393 + (29), redo 4 old)

50. Pow(x, n) (Medium) (fast power alf, binary search)
LintCode 169 · Tower of Hanoi (Medium) (recursion)
106. Construct Binary Tree from Inorder and Postorder Traversal (Medium) (divide and recursion / genius traversal one pass recursion)
LintCode 1593 · Construct Binary Tree from Preorder and Postorder Traversal (Medium) (same as above)
LintCode 1628 · Driving problem (Medium) (very nice non-standard BFS question)
Easy ones:
LintCode 1300 · Bash Game (Easy) (game theory basic)
LintCode 1106 · Maximum Binary Tree (Easy) (recursion)
redo old:
Design a Food Rating System (Medium) (SortedSet version)
Swap Nodes in Pairs (Medium) (practice linked list)
Construct Binary Tree from Preorder and Inorder Traversal (Medium)
Binary Search (easy) (practice recursion ver)

7/27 Wed: (Day 60, total new + 6 = 397 + (31), redo 6 old) 满60天纪念，leetcode新题397题+lintcode单独的31题总共428题。挺满意的，medium题230+，hard题的数量也接近60了，接下去要更加注重复习旧题，新题主要刷面经和没做的经典题了。

- [1059. All Paths from Source Lead to Destination](https://leetcode.com/problems/al ... ead-to-destination/) (Medium) (great graph question that need DFS instead of BFS, note to do)
- [1522. Diameter of N-Ary Tree](https://leetcode.com/problems/diameter-of-n-ary-tree/) (Medium) (DFS)
- [LintCode 1469 · Longest Path On The Tree](https://www.lintcode.com/problem/1469/description) (Medium) (great question) (DFS will strackoverflow, need BFS)
- [LintCode 1827 · Number of Ways to Stay in the Same Place After Some Steps II](https://www.lintcode.com/problem/1469/description) (Medium) (2D dp but useing 1D space otherwise MLE)
- [663. Equal Tree Partition](https://leetcode.com/problems/equal-tree-partition/) (Medium) (dfs subtree_sum)
- [425. Word Squares](https://leetcode.com/problems/word-squares/) (Hard) (backtrack) (wow a hashmap is better than Trie..)
- practice old:
- 22. Generate Parentheses (Meidum) (backtrack, pls practice time complexity analysis)
- 207. Course Schedule (Medium)
- 75. Sort Colors (Medium) (three pointers, pretty genius)
- 543. Diameter of Binary Tree (easy)
- 242. Valid Anagram (easy)
- 101. Symmetric Tree (easy) (great practice, slightly medium level. Did both recursion and iteration)

7/28 Thu: (Day 61, total new +6 = 399 + (35), redo 2 old)
- [LintCode 90 · k Sum II](https://www.lintcode.com/problem/90/) (Medium) (backtrack bc need output path)
- [LintCode 89 · k Sum](https://www.lintcode.com/problem/89/description) (Hard) (not need to output path so 3D dp)
- [890. Find and Replace Pattern](https://leetcode.com/problems/find-and-replace-pattern/) (Medium) (standard string compare)
- [251. Flatten 2D Vector](https://leetcode.com/problems/flatten-2d-vector/) (Meidum) (require O(1) space, two pointers or python yield and iterator)
- [LintCode 652 · Factorization](https://www.lintcode.com/problem ... mp;_from=collection) (Meidum) (backtrack) (finished but took 30 min, need more practice)
- [LintCode 291 · Second Diameter](https://www.lintcode.com/problem ... mp;_from=collection) (Medium) (graph theory + 3 times BFS) (经典题目，但没见过很难做出，难点不止是写还在于解释清楚算法正确性)
- practice old:
- 114. Flatten Binary Tree to Linked List (Morris traversal)
- 207. Course Schedule (did LintCode ver, try both DFS and BFS, DFS will stackoverflow)
- Wrote template for Morris traversal of binary tree to get preorder and inorder traversal in space O(1)
- Wrote template for topological sort (DFS version)

今天没咋做题，但开始准备别的方面了，学了些OOD，看了点BQ，刷题要继续减量让步给别的方面
7/29: (Day 62, total new +3 = 400 + (37), redo 2 old)
- [LintCode 262 · heir tree](https://www.lintcode.com/problem ... mp;_from=collection) (Meidum) (heir tree and use set to store disqualified) (question is actually badly design)
- [916. Word Subsets](https://leetcode.com/problems/word-subsets/) (Medium) (counter)
- [LintCode 92 · Backpack](https://www.lintcode.com/problem/92/) (Medium) (2D dp(i,x) = True or False)
- practice old:
- 256. paint house (Medium)
- 416. Partition Equal Subset Sum (Medium) (like Backpack question, 2D dp(i,x) = True or False)

7/30: (Day 62, total new +8 = 405 + (40), redo 0 old)
- [LintCode 20 · Dices Sum](https://www.lintcode.com/problem/20/description) (Medium) (2D dp number of ways)
- [688. Knight Probability in Chessboard](https://leetcode.com/problems/knight-probability-in-chessboard/) (Medium) (implementation / 3D dp with 2D rolling space)
- [LintCode 1702 · Distinct Subsequences II](https://www.lintcode.com/problem/1702/)(Hard) (O(N^2) 1d DP, or better O(N) DP)
- [LintCode 1607 · Profitable Schemes](https://www.lintcode.com/problem/1607/) (Hard) (wow 3D dp, need great design of DP state and relation)
- [2357. Make Array Zero by Subtracting Equal Amounts](https://leetcode.com/problems/ma ... ting-equal-amounts/) (Easy)
- [2358. Maximum Number of Groups Entering a Competition](https://leetcode.com/problems/ma ... ring-a-competition/) (Medium)
- [2359. Find Closest Node to Given Two Nodes](https://leetcode.com/problems/fi ... to-given-two-nodes/) (Medium)
- [2360. Longest Cycle in a Graph](https://leetcode.com/problems/longest-cycle-in-a-graph/) (Hard)

7/31: 休息 redo 1 old
- 62. Unique Paths (basic dp)

8/1: (Day 64, total new +1 = 406 + (40), redo 0 old) 躺平
- [378. Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kt ... in-a-sorted-matrix/) (Medium) (maxheap or binaryserach)

8/2: (Day 65, total new +1 = 407 + (40), redo 0 old) 躺平
- [401. Binary Watch](https://leetcode.com/problems/binary-watch/) (easy) (DFS)

回来还愿，NG full time上岸了。给offer的coding轮还挺难的medium to hard，所以暑期更新这个贴帮我坚持高强度刷了俩月题，还是很有帮助的。