Author: lcsqr
916. Word Subsets
Instead of dictionary, we can use an array of 26. Every medium has it’s own easy and hard…
388. Longest Absolute File Path
思路 按大自然的写法不难，问题在于需要了解”\t” “\n”是一个字符而不是两个。以及比起从前往后数数，用lstrip更快。 贴图的写法要点：对于不同路径，depth字典是会变的，但相同路径没有影响。 Stack方法：0 – 0, 0.1 – 0, 0.1, 0.1.1 – 0, 0.1, 0.1.1, 0.1.2 – 0, 0.2 （计算深度，当深度小于栈尾时，代表进入了另一个路径，把非路径的pop出栈）- 0, 0.2, 0.2.1
2185. Counting Words With a Given Prefix
Just practice writing Trie.
3402. Minimum Operations to Make Columns Strictly Increasing
Easy makes me happy.
3403. Find the Lexicographically Largest String From the Box I
Not hard. Should be aware of Boarder Cases ( numFrends == 1)
3404. Count Special Subsequences
Point: Turn multiplication to fraction Hard to realize “for r in range(4, n – 2): q = r – 2” part.
2168. Unique Substrings With Equal Digit Frequency
Actually, brute force can work due to constrains. However, if we count the frequency every time, the time complexity will be O(n**3), which may…
1427. Perform String Shifts
Don’t forget mod when dealing with shifting. A negative number a: a % b = (a + b) % b Anyway, easy makes me…