chapter 1 exercises 1,2,3 #2
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Lvcios
changed the title
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Thanks so much @Lvcios for your pull request! This is the first time I've had someone create a pull request in one of my projects so that's very exciting 😄
I've added a few comments that you can take a look at/address before merging. Let me know if you have questions!
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| // Space: O(n) |
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Nit:
| // Space: O(n) | |
| // Space: O(N) |
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Hi, I really, really, really, appreciate the feedback. I didn't expect it but it's great to learn from my mistakes.
I'll fix it as soon as I have enough time
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| // Space: O(n) | ||
| // Time: O(1) |
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| // Time: O(1) | |
| // Time: O(N) |
Distinct() requires an enumeration over the entire string so has an O(N) runtime
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| return summyString1 == summyString2; | ||
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This is a great idea, but unfortunately, it won't work in all cases :(
What you're doing is effectively creating a hash of the input and comparing to see if they're equal. This opens the opportunity for hash collisions.
Imagine a simplified example where characters have the following values:
A = 1
B = 2
C = 3
D = 4
The string ACC will have the following hash code:
A + C + C = 1 + 3 + 3 = 7
The string ABD will have the following hash code:
A + B + D = 1 + 2 + 4 = 7
These strings are going to be considered permutations using this algorithm, but in reality they're not permutations.
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| // Space: O(N) | ||
| // Time: O(N) | ||
| public static string ReplaceSpaces(char[] inputString) |
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This works if we're looking for another string, but in this case the question is asking for us to update the string in the original char array.
2 participants
Question1_1
I just want to contribute by adding a solution using LinQ. I'm not sure about the time and space complexity but this post can help: What guarantees are there on the run-time complexity (Big-O) of LINQ methods?
Question1_2
Solution by summing character numeric values in each string and comparing if the sum is the same.
Question1_3
Another o(N) solution using 2 arrays but without the real string length