• Count special palindromes in a string

    Count special palindromes in a string

    Please Login in order to post a comment. Really simple 3 pass solution: 1. Build a list of tuples such that the string "aaabbc" can be squashed down to [ "a", 3"b", 2"c", 1 ]. Implemented your logic in Java. Had to tweak the code to optimise it and also reduced it to 2 passes. I also wanted to solve it with a single pass and no extra structures. I struggled much more than I was hoping for It would be very helpful. If you could provide the explanation of your code, or what is the approach.!

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    I used it together with some luck that allowed me to find more small and meaningful test cases to debug a similar idea I had, only that it works strictly forward rather than expanding from the middle:.

    Checks if it forms a palindrome. The condition for that is the current element should have count 1, and we take the least of the counts on either side of the current element if they are equal. This is the 3rd pass, it tries to find a letter cluster with length 1, and its left letter cluster and right letter cluster are the same letter. For example bbbabb. And number of the palindrome is limited by the min length of those two side letter cluster.

    For example, it has "bab", "bbabb", two palindrome, equals to the length of right letter cluster. I am sorry for my English. Hope you can understand. How this logic will work to count 'cbbabbc'? Because this is special palindrome string, case 2: All characters except the middle one are the same, e. Since "cbbabbc" contains two different letters on either side of the dividing letter, it's not counted.

    There are many applications using this sequence. In this problem it's possible to find the number of repeated char combinations throught triangular number sequence.

    Here an example:. Hello, can you explain your logic without using regular expessions?

    Palindrome permutations of a string

    How can I do this problem just using the triangle number? I'm not sure if is possible to solve the problem using triangular number only. Triangular number is just an especific sequence and in this solution, triangular number is part of the solution. I'll try explain the solution step by step :. Example of this step is: aaaa has the combination of:. I little late but I'll try to explain. So this formula yeilds only integer results.

    count special palindromes in a string

    Thanks for the logic and style, I'm sure many have learned from it!I converted this code in python and tried to run that code. But the loop where all sub strings with same characters are counted, does not end. Can you share this code in python? Widget Recent Post No. Widget Random Post No.

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    PageNavi Results No. Labels Max-Results No. Menu Home About Contact Advertise. Given a string, determine how many special palindromic substrings can be formed from it.

    Function Description. It should return an integer representing the number of special palindromic substrings that can be formed from the given string. Input Format. The second line contains the string. Each character of the string is a lowercase alphabet. Output Format.

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    Print a single line containing the count of total special palindromic substrings. Sample Input 0. Sample Output 0. Explanation 0. Sample Input 1. Sample Output 1. Explanation 1. Sample Input 2. Sample Output 2. Explanation 2. The simplest solution is to check the given condition for every possible substrings and count the valid ones.

    To do this in a little better way we can store the cumulative sum of the occurrences of each character in the string and again count the valid ones by using memoization. So, we count total substrings from both cases.

    Problem Setter's code:. Unknown March 20, at PM. Swarnveer April 10, at AM. Newer Post Older Post Home.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Code Review Stack Exchange is a question and answer site for peer programmer code reviews. It only takes a minute to sign up. Code is working fine as can be checked on ideone.

    Note: Here fout has been replaced with cout. A special palindromic substring is any substring of a string which meets one of those criteria. Given a string, determine how many special palindromic substrings can be formed from it. Complete the substrCount function in the editor below. It should return an integer representing the number of special palindromic substrings that can be formed from the given string.

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    The first line contains an integer, nthe length of s. The second line contains the string. See for example. All tests can be done directly on the original string s. As an example.

    count special palindromes in a string

    The following approach seems more efficient to me:. The number of substrings with all identical characters e. To determine the number of substrings where characters except the middle one are the same e. Example: The string "mnonopoo" has the following sequences of contiguous identical characters.

    The number of substrings where all characters except the middle one are the same around each character are. If you want to create a reverse of a range, just initialize the copy with reverse-iterators instead of copying and then reversing. If you want to know whether a range is all copies of the same element except the middle, take a look at std::count :. Sign up to join this community. The best answers are voted up and rise to the top.

    Home Questions Tags Users Unanswered. Asked 1 year, 7 months ago.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

    Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I want to find out all possible palindromes that can be possible using substrings from a given string.

    What are palindromes? A palindrome is a symmetrical string, which means it must have a center pivot! The pivot may be one of the following:. If you're comfortable busting out some heavyweight data structures, it's possible to do this in time O nthough I'll admit that this isn't something that will be particularly easy to code up. Tool One: Generalized Suffix Trees. A generalized suffix tree is data structure that, intuitively, is a trie containing all suffixes of two strings S and T, but represented in a more space-efficient way.

    A lowest common ancestor query structure or LCA query is a data structure built around a particular tree. It's designed to efficiently answer queries of the form "given two nodes in the tree, what is their lowest common ancestor?

    Importantly, a generalized suffix tree for two strings of length m can be built in time O mand an LCA query can be built in time O m such that all queries take time O 1.

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    These are not obvious runtimes; the algorithms and data structures needed here were publishable results when they were first discovered. Assuming we have these two structures, we can build a third data structure, which is what we'll use to get our final algorithm:. A longest common extension query data structure or LCE query is a data structure built around two strings S and T. It supports queries of the following form: given an index i into string S and an index j into string T, what is the length of the longest string that appears starting at index i in S and index j in T?

    On the other hand, if we did an LCE query starting at index 4 in string S and index 0 in string T, we'd get back the string N. More strictly, the LCE query structure doesn't actually return the actual string you'd find at both places, but rather its length.

    The technique for doing so involves building a generalized suffix tree for the two strings, then constructing an LCA data structure on top. The key insight is that the LCE starting at position i in string S and j in string T is given by the lowest common ancestor of suffix i of string S and suffix j of string T in the suffix tree.

    The LCE structure is extremely useful for this problem. To see why, let's take your sample string abbcbbd. Now, consider both that string and its reverse, as shown here:. Every palindrome in a string takes one of two forms. First, it can be an odd-length palindrome.

    A palindrome like that has some central character c, plus some "radius" stretching out forwards and backwards from that center. For example, the string bbcbb is an odd-length palindrome with center c and radius bb.Given a String s, count all special palindromic substrings of size greater than 1. A Substring is called special palindromic substring if all the characters in the substring are same or only the middle character is different for odd length. Simple Solution is that we simply generate all substrings one-by-one and count how many substring are Special Palindromic substring.

    This solution takes O n 3 time. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute. See your article appearing on the GeeksforGeeks main page and help other Geeks. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Writing code in comment? Please use ide. Count special palindromes in a String Split the given string into Primes : Digit DP Find lexicographically smallest string in at most one swaps Remove odd frequency characters from the string Longest Palindrome in a String formed by concatenating its prefix and suffix Longest palindrome formed by concatenating and reordering strings of equal length Check if given string contains all the digits Count maximum occurrence of subsequence in string such that indices in subsequence is in A.

    Python3 program to count special. Function to count special. Palindromic substring. Case : 1. Case 2: Count all odd length. Special Palindromic substring. Previous same character count.

    This code is contributed by mits. Min sameChar[j - 1]. Write CountSpecialPalindrome str. Recommended Posts: Count maximum-length palindromes in a String Program to count vowels, consonant, digits and special characters in string. Check if suffix and prefix of a string are palindromes Move all special char to the end of the String Count Uppercase, Lowercase, special character and numeric values Reverse a string without affecting special characters Split a string in equal parts such that all parts are palindromes Check if a string can be rearranged to form special palindrome Split numeric, alphabetic and special symbols from a String Check if count of Alphabets and count of Numbers are equal in the given String Find the count of palindromic sub-string of a string in its sorted form Count of times second string can be formed from the characters of first string Program to print all palindromes in a given range Count subsequences in first string which are anagrams of the second string Count occurrences of a string that can be constructed from another given string.

    Check out this Author's contributed articles. Load Comments.SQL is a really cool language. I can write really complex business logic with this logic programming language. I was again thrilled about SQL recently, at a customer site:. Writing some nifty SQL queries for a customer.

    Wondering why anyone would even consider using a 3GL for any business logic at all?? But whenever I tweet something like the above, the inevitable happened.

    I was nerd sniped. Given a string, find all substrings from that string, which are palindromes. Challenge accepted!

    This is done with the WITH clause. In order to look for palindromes, the algorithm used here lists, for each word, the character index of each individual character in the word:.

    The characters to the left and to the right of such a character must be the same and so on. If you want to tune the query, you could prevent generating them in the first place. Now comes the interesting part. Recursively fanning out from a starting character to find more palindromes, stopping the fanning out as soon as the new candidate is no longer a plaindrome:.

    That table has 4 columns:. There are a total of 8 distinct palindromes contained in this word and believe it or not, the word exists, too. Pronunciation is another thing. Again, feel free to play around with this on SQLFiddleor, much better, provide a cool palindrome algorithm implementation in your favourite language in the comments section, or on Twitter:.

    OK, my friends.

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    Here you go. View all posts by lukaseder. I did a simple nested loops solution. Yeah, nice. Thanks for sharing. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account.

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    count special palindromes in a string

    This site uses Akismet to reduce spam. Learn how your comment data is processed. Skip to content SQL is a really cool language. Published by lukaseder. Next Post jOOQ 3. Thanks Lukas for sharing it! Leave a Reply Cancel reply Enter your comment hereThe substrings with different start indexes or end indexes are counted as different substrings even they consist of same characters.

    Let N be the length of the string. The middle of the palindrome could be in one of 2N - 1 positions: either at letter or between two letters. For each center, let's count all the palindromes that have this center. For each possible palindrome center, let's expand our candidate palindrome on the interval [left, right] as long as we can.

    Space Complexity: O 1 O 1 O 1. Manacher's algorithm is a textbook algorithm that finds in linear time, the maximum size palindrome for any possible palindrome center.

    If we had such an algorithm, finding the answer is straightforward. Then, limited to the interval with radius right - i and center ithe situation for Z[i] is the same as for Z[j]. Notice that limited to the interval [center - right - centerright] the interval with center center and right-boundary rightthe situation for i and j is a reflection of something we have already computed.

    Now, why is this algorithm linear? Say the longest palindrome with some given center C has radius R. Then, the substring with center C and radius R-1, R-2, R-3, Example: abcdedcba is a palindrome with center eradius 4: but ededcdedcbcdedcband abcdedcba are all palindromes. We are dividing by 2 because we were using half-lengths instead of lengths.

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    For example we actually had the palindrome a b c d e d c b aso our length is twice as big. As discussed above, the complexity is linear. Lets say the length of the string is 3 and string is "aba". My questions. Leetcode team should really improve on the quality of the solution descriptions. Explanation for approach one is horrible and hard to understand.

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