打卡刷利口刷面经备战BB帖

6/26
1. 117
2. 332 reconstruct itinerary use priority queue as values in map, and dfs
3. 113 sum path2 dfs

6/27
1. 542 01 matrix use bfs start from 0 circle by circle
2. 129 sum root to leaf numbers dfs
3. 494 target sum dfs res as global vairiable

6/28
1. 364 nested list weight sum2, find depth local variable, find sum local variable
2. 565 array nesting  

6/29
1. 513 最左下角node  dfs bfs两种解法
2. 742 closest leaf in a bt
3. 210 course schedule 2 跟1做法基本一样 就是把课程打印出来
4. 515 find largest value in each row bfs and dfs
5. 366 find leaves of bt 把求树高和dfs结合 最底层是0，与res的index结合

6/30
1. 67 add binary
2. 43 multiply string很有意思的一道题 乘法法则 建一个数组存

7/1
1. 285 inorder successor in bst iterative和recursive都要会
2. 94 inorder traversal 用cur stack
3. 43 multiply string
4. 79 word search dfs 每一个点作为起点， 若是向四周扩散，找第二个字符，boolean数组判断是否访问，注意reset数组如果不是一个valid 点
5.168 excel sheet column title n--   然后n%26  注意大写字母表达方式 (char)('A'+n%26)

7/2
1. 171 excel sheet column number
2. 647 palindromic substrings
3. 127 word ladder

7/6
1. 341 flatten nested list iterator
2. 251 flatten 2d vector
3. 339 nested list weight sum 递归
4. 364 nested list weight sum 2 递归
5. 281 zigzag iterator 三个iterator 交换
6. 284 peeking iterator 一个next integer cache the next element

7/8
practice class 13 treeset hashset linkedhashset, hashmap implementation: object->hashcode, handle collision, operations. hashcode equals overwrite together
7/9
301
10 regular expression matching 动态规划 一些规律 .或相同字符，从左上角下来；* 前上第二个值 或者前左第二个值
7/14
1. 16 3sum closest
2. 15 3sum
259. 3sum smaller

7/16
1. 621 task schedule
2. find largest subtree sum in a tree
3. 31. next bigger permutation
4. 238 product of array except self

7/21
325

7/23
28 implement strstr()
38 count and say recursive count the number of num
209 relate to 325 min size subarray sum, when reach sum, delete from left
718 relate to 209 max length of repeated subarray, brute force, watch out the condition
278 first bad version, binary search

7/31
rome to integer
integer to rome
3 sum
never stop leetcoding a...