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Print longest palindrome word in a sentence
  • Difficulty Level : Easy
  • Last Updated : 16 Jan, 2019

Given a string str, the task is to print longest palindrome word present in the string str.

Examples:

Input : Madam Arora teaches Malayalam
Output: Malayalam
Explanation: The string contains three palindrome words (i.e., Madam, Arora, Malayalam) but the length of Malayalam is greater than the other two.

Input : Welcome to GeeksforGeeks
Output : No Palindrome Word
Explanation:The string does not contain any palindrome word so the output is No Palindrome Word.

Approach:

  • longestPalin() function finds the longest palindrome word by extracting every word of the string and passing it to checkPalin() function. An extra space is added in the original string to extract last word.
  • checkPalin() function checks if the word is palindrome. It returns true if word is palindrome else returns false. It makes sure that empty strings are not counted as palindrome as the user may enter more than one spaces in between or at the beginning of the string.

C++




/* C++ program to print longest palindrome
word in a sentence and its length*/
#include <iostream>
#include <algorithm>
#include <string>
  
using namespace std;
  
// Function to check if a
// word is palindrome
bool checkPalin(string word)
{
    int n = word.length();
  
    // making the check case
    // case insensitive
    // word = word.toLowerCase();
    transform(word.begin(), word.end(), 
              word.begin(), ::tolower);
  
    // loop to check palindrome
    for (int i = 0; i < n; i++, n--)
        if (word[i] != word[n - 1])
            return false;
  
    return true;
}
  
// Function to find longest
// palindrome word
string longestPalin(string str)
{
      
    // to check last word for palindrome
    str = str + " ";
  
    // to store each word
    string longestword = "", word = "";
  
    int length, length1 = 0;
    for (int i = 0; i < str.length(); i++)
    {
        char ch = str[i];
  
        // extracting each word
        if (ch != ' ')
            word = word + ch;
        else {
            length = word.length();
            if (checkPalin(word) && 
                       length > length1)
            {
                length1 = length;
                longestword = word;
            }
  
            word = "";
        }
    }
  
    return longestword;
}
  
// Driver code
int main()
{
    string s = "My name is ava and i love" 
                         " Geeksforgeeks";
  
    if (longestPalin(s) == "")
        cout<<"No Palindrome"<<" Word";
    else
        cout<<longestPalin(s);
    return 0;
}
  
// This code is contributed by Manish 
// Shaw (manishshaw1)


Java




/*Java program to print longest palindrome
word in a sentence and its length*/
  
public class GFG {
  
    // Function to check if a
    // word is palindrome
    static boolean checkPalin(String word)
    {
        int n = word.length();
  
        // making the check case
        // case insensitive
        word = word.toLowerCase();
  
        // loop to check palindrome
        for (int i = 0; i < n; i++, n--)
            if (word.charAt(i) != 
                       word.charAt(n - 1))
                return false;
  
        return true;
    }
  
    // Function to find longest
    // palindrome word
    static String longestPalin(String str)
    {
        // to check last word for palindrome
        str = str + " ";
  
        // to store each word
        String longestword = "", word = "";
  
        int length, length1 = 0;
        for (int i = 0; i < str.length(); i++) 
        {
            char ch = str.charAt(i);
  
            // extracting each word
            if (ch != ' ')
                word = word + ch;
            else {
                length = word.length();
                if (checkPalin(word) && 
                             length > length1)
                {
                    length1 = length;
                    longestword = word;
                }
  
                word = "";
            }
        }
  
        return longestword;
    }
  
    // Driver code
    public static void main(String args[])
    {
        String s = new String("My name is ava "
                + "and i love Geeksforgeeks");
  
        if (longestPalin(s) == "")
            System.out.println("No Palindrome"
                            + " Word");
        else
            System.out.println(longestPalin(s));
    }
}


Python3




# Python 3 program to print longest palindrome
# word in a sentence and its length
  
# Function to check if a word is palindrome
def checkPalin(word):
  
    n = len(word)
  
    # making the check case
    # case insensitive
    word = word.lower()
  
    # loop to check palindrome
    for i in range( n):
        if (word[i] != word[n - 1]):
            return False
        n -= 1
  
    return True
  
# Function to find longest
# palindrome word
def longestPalin(str):
      
    # to check last word for palindrome
    str = str + " "
  
    # to store each word
    longestword = ""
    word = ""
  
    length1 = 0
    for i in range(len(str)):
        ch = str[i]
  
        # extracting each word
        if (ch != ' '):
            word = word + ch
        else :
            length = len(word)
            if (checkPalin(word) and
                length > length1):
                length1 = length
                longestword = word
  
            word = ""
  
    return longestword
  
# Driver code
if __name__ == "__main__":
      
    s = "My name is ava and i love Geeksforgeeks"
  
    if (longestPalin(s) == ""):
        print("No Palindrome Word")
    else:
        print(longestPalin(s))
  
# This code is contributed by ita_c


C#




/* C# program to print longest palindrome
word in a sentence and its length*/
using System;
class GFG 
{
    // Function to check if a
    // word is palindrome
    static bool checkPalin(string word)
    {
        int n = word.Length;
      
        // making the check case
        // case insensitive
        word = word.ToLower();
      
        // loop to check palindrome
        for (int i = 0; i < n; i++, n--)
            if (word[i] != word[n - 1])
                return false;
      
        return true;
    }
      
    // Function to find longest
    // palindrome word
    static string longestPalin(string str)
    {
          
        // to check last word for palindrome
        str = str + " ";
      
        // to store each word
        string longestword = "", word = "";
      
        int length, length1 = 0;
        for (int i = 0; i < str.Length; i++)
        {
            char ch = str[i];
      
            // extracting each word
            if (ch != ' ')
                word = word + ch;
            else {
                length = word.Length;
                if (checkPalin(word) && 
                        length > length1)
                {
                    length1 = length;
                    longestword = word;
                }
      
                word = "";
            }
        }
      
        return longestword;
    }
      
    // Driver code
    public static void Main()
    {
        string s = "My name is ava and i"
           + " love Geeksforgeeks";
      
        if (longestPalin(s) == "")
            Console.Write("No Palindrome Word");
        else
            Console.Write(longestPalin(s));
    }
  
// This code is contributed by Manish 
// Shaw (manishshaw1)


Output:

ava

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