9月刷题/Mock interview接龙活动（缺米刷题的来）

9.20 Day 40

9/20 打卡， 两道medium backtracking
22. Generate Parentheses
46. Permutations

9.20打卡

378 Kth Smallest Element in a Sorted Matrix   
668 Kth Smallest Number in Multiplication Table   
719 Find K-th Smallest Pair Distance   
786 K-th Smallest Prime Fraction   

打卡

加两道 梯子

求加米，谢谢大家！

9/20 打卡第20天， 刷了1道题

980. Unique Paths III
backtracking, depth-first-search
to save space, in place replace grid[i][j] from 0 to -2,
after finishing the search in this branch, change it back to 0

9.20 这个帖子第二天
bfs重新过了一遍

两道题

1. same tree
2. height of tree

打卡
Split a String Into the Max Number of Unique Substrings
Rearrange Spaces Between Words
Unique Paths III