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Longest Common Prefix in an Array

Vikrant Pandey answered on May 17, 2022 Popularity 9/10 Helpfulness 2/10

answer Longest Common Prefix in an Array

related Longest Common Prefix Method 2

Longest Common Prefix in an Array

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// Java Program to find the longest common
// prefix of the given words
public class Longest_common_prefix {
      
    // Alphabet size (# of symbols)
    static final int ALPHABET_SIZE = 26;
       
    // Trie node
    static class TrieNode
    {
        TrieNode[] children = new TrieNode[ALPHABET_SIZE];
       
        // isLeaf is true if the node represents
        // end of a word
        boolean isLeaf;
          
        // constructor
        public TrieNode() {
            isLeaf = false;
            for (int i = 0; i < ALPHABET_SIZE; i++)
                children[i] = null;
        }
    };
       
    static TrieNode root;
    static int indexs;
       
    // If not present, inserts the key into the trie
    // If the key is a prefix of trie node, just marks
    // leaf node
    static void insert(String key)
    {
        int length = key.length();
        int index;
       
        TrieNode pCrawl = root;
       
        for (int level = 0; level < length; level++)
        {
            index = key.charAt(level) - 'a';
            if (pCrawl.children[index] == null)
                pCrawl.children[index] = new TrieNode();
       
            pCrawl = pCrawl.children[index];
        }
       
        // mark last node as leaf
        pCrawl.isLeaf = true;
    }
       
    // Counts and returns the number of children of the
    // current node
    static int countChildren(TrieNode node)
    {
        int count = 0;
        for (int i=0; i<ALPHABET_SIZE; i++)
        {
            if (node.children[i] != null)
            {
                count++;
                indexs = i;
            }
        }
        return (count);
    }
       
    // Perform a walk on the trie and return the
    // longest common prefix string
    static String walkTrie()
    {
        TrieNode pCrawl = root;
        indexs = 0;
        String prefix = "";
       
        while (countChildren(pCrawl) == 1 &&
                pCrawl.isLeaf == false)
        {
            pCrawl = pCrawl.children[indexs];
            prefix += (char)('a' + indexs);
        }
        return prefix;
    }
       
    // A Function to construct trie
    static void constructTrie(String arr[], int n)
    {
        for (int i = 0; i < n; i++)
            insert (arr[i]);
        return;
    }
       
    // A Function that returns the longest common prefix
    // from the array of strings
    static String commonPrefix(String arr[], int n)
    {
        root = new TrieNode();
        constructTrie(arr, n);
       
        // Perform a walk on the trie
        return walkTrie();
    }
       
    // Driver program to test above function
    public static void main(String args[])
    {
        String arr[] = {"geeksforgeeks", "geeks",
                        "geek", "geezer"};
        int n = arr.length;
       
        String ans = commonPrefix(arr, n);
       
        if (ans.length() != 0)
            System.out.println("The longest common prefix is "+ans);
        else
            System.out.println("There is no common prefix");
    }
}
// This code is contributed by Sumit Ghosh

Popularity 9/10 Helpfulness 2/10 Language java

Source: www.geeksforgeeks.org

Tags: java prefix

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Contributed on Jul 17 2022

Vikrant Pandey

0 Answers Avg Quality 2/10

Closely Related Answers

Longest Common Prefix Method 2

Comment

class Solution:
    def longestCommonPrefix(self, strs):
        result = []
        for i in zip(*strs):
            if len(set(i)) != 1:
                break
            result.append(i[0])
        return "".join(result)     

"""The zip() method returns a zip object, which is an iterator of tuples where 
the first item in each passed iterator is paired together, and then the second item in 
each passed iterator are paired together etc.
If the passed iterators have different lengths, the iterator with the least items 
decides the length of the new iterator.

set() method is used to convert any of the iterable to sequence of iterable elements 
with distinct elements, commonly called Set. 
"""                 
 
        

Task = Solution()
print("3a. ",Task.longestCommonPrefix(["flower","flow","flight"]))
print("3b. ",Task.longestCommonPrefix(["dog","racecar","car"]))

Popularity 10/10 Helpfulness 3/10 Language python

Source: Grepper

Tags: prefix pr

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Contributed on May 17 2022

Kingsley Atuba

0 Answers Avg Quality 2/10

Longest Common Prefix in an Array

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Longest Common Prefix in an Array

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