get longest palindrome #704
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+ Hits 20786 21037 +251
+ Misses 1198 1155 -43 ☔ View full report in Codecov by Sentry. |
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#703 It's not clear why the other tests didn't pass, I didn't change any of the other code. |
It is just some random failure - some tests in this repository are not deterministic. In general - this is not a big deal. |
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I thought it was my problem..... |
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In any case, the question about |
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aabb theoretically outputs either aa or bb, here it only outputs bb |
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I think that should be allowed. |
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The code looks quite good. Please update the doc string by adding some explanation how do you find the longest palindrome, adding a sentence about non-unique solution (I guess, your function returns the one most on the right). Also, please add a test case with |
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This compilation error is a machine problem？ |
| } | ||
| let s: Vec<char> = s.chars().collect(); | ||
| let n = s.len(); | ||
| // dp indicates whether it is a palindrome |
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I have no idea what do you mean here. Maybe try to describe that dp[a][b] is?
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It's a bit redundant here, dp is the string of the dynamic programming process
| let n = s.len(); | ||
| // dp indicates whether it is a palindrome | ||
| let mut dp = vec![vec![true; n]; n]; | ||
| // res record the indexes before and after the palindrome |
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Are you sure about the before part? I am not mistaking, the res[0] is the index of the first character of the resulting palindrome.
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res[0] is the index at the beginning of the palindrome，res[1] is the index of the end of the palindrome
| let mut res = (0, 0); | ||
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| // form filling strategy: fill in the form by length | ||
| // k denotes the length of the palindrome, the further you traverse, the longer it is |
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Why not use use palindrome_length instead of k?
| // strings of 2 equal characters are palindromes | ||
| dp[i][i + k] = s[i] == s[i + 1]; | ||
| } else { | ||
| // a string that is equal on both sides and has an iambic palindrome in the middle is also an iambic palindrome |
| dp[i][i + k] = (s[i] == s[i + k]) && dp[i + 1][i + k - 1]; | ||
| } | ||
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| // update palindrome length, record index |
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| // update palindrome length, record index |
| // Theoretically it is possible to return either aa or bb, | ||
| // there are multiple palindromes of the same length, here only the rightmost one is returned |
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I am still thinking about that. In case of "aabb", the longest palindrome does not exist. "aa" and "bb" are palindromes, but they have equal length.
The longest palindrome must be unique.
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You have a point, I don't think it's necessary to get hung up on whether the longest is unique or not,
it's possible for a tournament to have a double winner as well
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@changweidalaifu6 after rethinking the whole thing, I am not sure anymore if this contribution is suitable for this repository. The problem is very specific (it is a leetcode problem after all) and quite cumbersome to state properly (well, the function should be called something like |
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It's true that it's a bit buttoned up, but it's very tight |
Updated code and added comments