冲谷日记

Maximize Capital (hard)
Given a set of investment projects with their respective profits, we need to find the most profitable projects. We are given an initial capital and are allowed to invest only in a fixed number of projects. Our goal is to choose projects that give us the maximum profit.
Input: Project Capitals=[0,1,2,3], Project Profits=[1,2,3,5], Initial Capital=0, Number of Projects=3
Output: 8
Algorithm:
Use two heaps. first put capital and it's index which is the project id into a minheap, based on the initial capital, choose all the projects that within the capital. Then put the project id and it's profits tuple into the maxheap and pop the maxheap. Then update the capital to see how much money we have now. Repeat this process for k times, where k is number of projects we can choose.

Given a string, find all of its permutations preserving the character sequence but changing case.
Input: "ab7c"
Output: "ab7c", "Ab7c", "aB7c", "AB7c", "ab7C", "Ab7C", "aB7C", "AB7C"

problem itself is not hard, it's just simply select and replace the alpha char like subsets. Tricky thing are:
How do you replace the lower case with the upper case?
We can use python swapcase() function. However, we just want to swap one single char at a time, we have to make ii to list, swap case, then join it back as string.

1. 
   
2.       string = list(permutations[j])
   
3.       if string.isnumeric():
   
4.         continue
   
5.       string = string.swapcase()
   
6.       permutations.append(''.join(string))
   

复制代码

[i][/i]

Order-agnostic Binary Search (easy)
Ceiling of a Number (medium)
Next Letter (medium)
Number Range (medium)
Search in a Sorted Infinite Array (medium)

binary search tree刷起来还是很快，5道题上班刷完

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