Print longest palindrome word in a sentence
Last Updated : 11 Apr, 2023
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 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)); } } # 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 <script> /*Javascript program to print longest palindrome word in a sentence and its length*/ // Function to check if a // word is palindrome function checkPalin(word) { let n = word.length; // making the check case // case insensitive word = word.toLowerCase(); // loop to check palindrome for (let i = 0; i < n; i++, n--) if (word[i] != word[n-1]) return false; return true; } // Function to find longest // palindrome word function longestPalin(str) { // to check last word for palindrome str = str + " "; // to store each word let longestword = "", word = ""; let length, length1 = 0; for (let i = 0; i < str.length; i++) { let 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 let s="My name is ava " + "and i love Geeksforgeeks"; if (longestPalin(s) == "") document.write("No Palindrome" + " Word"); else document.write(longestPalin(s)); // This code is contributed by rag2127 </script> /* 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) Time complexity : O(n^2)
Space complexity : O(n)
Method #2:Using sorted() method in Python:
- The idea is to split the words of the string into a list .
- Traverse the list and append all palindromic words to new list
- Sort the newlist in increasing order of length of words using the sorted() method.
- Finally, print the last string present in the list.
Below is the implementation of the above approach.:
C++ // C++ program for the above approach #include <iostream> #include <vector> #include <algorithm> using namespace std; bool isPalindrome(string s) { return s == string(s.rbegin(), s.rend()); } void largestPalin(vector<string> s) { // Taking new list vector<string> newlist; // Traverse the list for (string word : s) { if (isPalindrome(word)) { newlist.push_back(word); } } // Using sorted() method sort(newlist.begin(), newlist.end(), [](string a, string b) { return a.size() < b.size(); }); // Print last word cout << newlist.back() << endl; } // Driver Code int main() { // Given string string str = "My name is ava and i love Geeksforgeeks"; vector<string> words; string word; for (char c : str) { if (c == ' ') { words.push_back(word); word.clear(); } else { word += c; } } if (!word.empty()) { words.push_back(word); } largestPalin(words); return 0; } // This code is contributed by Prajwal Kandekar import java.util.ArrayList; import java.util.Collections; public class Main { // Function to check if a string is a palindrome public static boolean isPalindrome(String s) { return s.equals( new StringBuilder(s).reverse().toString()); } // Function to find the largest palindrome in a list of // words public static void largestPalin(ArrayList<String> s) { // Create a new list to store all the palindromes // found ArrayList<String> newlist = new ArrayList<>(); // Iterate over each word in the input list for (String word : s) { // Check if the current word is a palindrome if (isPalindrome(word)) { // If it is, add it to the new list newlist.add(word); } } // Sort the new list in ascending order of length Collections.sort(newlist, (a, b) -> a.length() - b.length()); // Print the largest palindrome (last element in the // sorted list) System.out.println(newlist.get(newlist.size() - 1)); } public static void main(String[] args) { // Input string to be processed String str = "My name is ava and i love Geeksforgeeks"; // Create a list to store all the words in the input // string ArrayList<String> words = new ArrayList<>(); // Create a string builder to build each word from // the input string StringBuilder word = new StringBuilder(); // Iterate over each character in the input string for (char c : str.toCharArray()) { // If the current character is a space, the // current word is complete if (c == ' ') { // Add the current word to the list of words words.add(word.toString()); // Reset the string builder to build the // next word word.setLength(0); } else { // Otherwise, append the current character // to the current word word.append(c); } } // If there is a word left in the string builder, // add it to the list of words if (word.length() > 0) { words.add(word.toString()); } // Find the largest palindrome in the list of words largestPalin(words); } } # Python3 program for the above approach def ispalindrome(string): if(string == string[::-1]): return True else: return False def largestPalin(s): # Taking new list newlist = [] # Traverse the list for i in s: if(ispalindrome(i)): newlist.append(i) # Using sorted() method s = sorted(newlist, key=len) # Print last word print(s[len(s)-1]) # Driver Code if __name__ == "__main__": # Given string s = "My name is ava and i love Geeksforgeeks" # Convert string to list l = list(s.split(" ")) largestPalin(l) # This code is contributed by vikkycirus <script> // JavaScript program for the above approach function ispalindrome(string){ let temp = string temp = temp.split('').reverse().join('') if(string == temp) return true else return false } function largestPalin(s){ // Taking new list let newlist = [] // Traverse the list for(let i of s){ if(ispalindrome(i)) newlist.push(i) } // Using sorted() method newlist.sort((a,b)=>a.length - b.length) s = newlist // Print last word document.write(s[s.length-1],"</br>") } // Driver Code // Given string let s = "My name is ava and i love Geeksforgeeks" // Convert string to list let l = s.split(" ") largestPalin(l) // This code is contributed by shinjanpatra </script> // C# program for the above approach using System; using System.Collections.Generic; using System.Linq; public class Program { // Function to check if a string is a palindrome public static bool IsPalindrome(string s) { return s.Equals(new string(s.Reverse().ToArray())); } // Function to find the largest palindrome in a list of // words public static void LargestPalin(List < string > s) { // Create a new list to store all the palindromes // found List < string > newList = new List < string > (); // Iterate over each word in the input list foreach(string word in s) { // Check if the current word is a palindrome if (IsPalindrome(word)) { // If it is, add it to the new list newList.Add(word); } } // Sort the new list in ascending order of length newList.Sort((a, b) => a.Length - b.Length); // Print the largest palindrome (last element in the // sorted list) Console.WriteLine(newList[newList.Count - 1]); } public static void Main(string[] args) { // Input string to be processed string str = "My name is ava and i love Geeksforgeeks"; // Create a list to store all the words in the input // string List < string > words = new List < string > (); // Create a string builder to build each word from // the input string System.Text.StringBuilder word = new System.Text.StringBuilder(); // Iterate over each character in the input string foreach(char c in str) { // If the current character is a space, the // current word is complete if (c == ' ') { // Add the current word to the list of words words.Add(word.ToString()); // Reset the string builder to build the // next word word.Clear(); } else { // Otherwise, append the current character // to the current word word.Append(c); } } // If there is a word left in the string builder, // add it to the list of words if (word.Length > 0) { words.Add(word.ToString()); } // Find the largest palindrome in the list of words LargestPalin(words); } } // Contributed by adityasharmadev01 Output:
ava
Method #3:Using filter() method in Python:
- First, the string is converted into a list of words using the re module.
- Then the filter function is applied to the list of word to, using ispalindrome function to filter out only the palindrome words.
- After max, the function is applied using the len as key to get a word with max length
C++ #include <algorithm> #include <iostream> #include <regex> #include <string> using namespace std; bool ispalindrome(string word) { return word == string(word.rbegin(), word.rend()); } void largestPalin(string s) { // Convert string to vector of words regex pattern(R "(\b\w+\b)"); vector<string> words( sregex_token_iterator(s.begin(), s.end(), pattern), sregex_token_iterator()); // Using remove_if() and erase() functions to remove // non-palindrome words words.erase(remove_if(words.begin(), words.end(), [](string word) { return !ispalindrome(word); }), words.end()); // Using max_element() function to find the word with // the maximum length auto it = max_element( words.begin(), words.end(), [](string a, string b) { return a.length() < b.length(); }); // Printing the largest palindrome cout << *it << endl; } int main() { string s = "My name is ava and i love Geeksforgeeks"; largestPalin(s); return 0; } // Java program for the above approach import java.util.ArrayList; import java.util.List; public class Main { public static boolean isPalindrome(String word) { return word.equals( new StringBuilder(word).reverse().toString()); } public static void largestPalin(String s) { // Convert string to list of words String[] words = s.split("\\W+"); List<String> palindromeWords = new ArrayList<>(); // Using filter() function to filter palindrome // words for (String word : words) { if (isPalindrome(word)) { palindromeWords.add(word); } } // Using max() function to find the word with the // maximum length String largestPalindrome = palindromeWords.stream() .max((a, b) -> Integer.compare(a.length(), b.length())) .orElse(null); System.out.println(largestPalindrome); } public static void main(String[] args) { String s = "My name is ava and i love Geeksforgeeks"; largestPalin(s); } } // Contributed by adityasha4x71 import re def ispalindrome(word): return word == word[::-1] def largestPalin(s): # Convert string to list of words words = re.findall(r'\b\w+\b', s) # Using filter() function to filter palindrome words palindrome_words = filter(ispalindrome, words) # Using max() function to find the word with the maximum length largest_palindrome = max(palindrome_words, key=len) print(largest_palindrome) # Driver Code if __name__ == "__main__": s = "My name is ava and i love Geeksforgeeks" largestPalin(s)
// JavaScript program for above approach function isPalindrome(word) { return word === word.split('').reverse().join(''); } function largestPalin(s) { // Convert string to array of words const words = s.match(/\b\w+\b/g); // Using filter() method to filter palindrome words const palindromeWords = words.filter(isPalindrome); // Using reduce() method to find the word with the maximum length const largestPalindrome = palindromeWords.reduce((a, b) => a.length >= b.length ? a : b, ""); console.log(largestPalindrome); } // Driver Code const s = "My name is ava and i love Geeksforgeeks"; largestPalin(s); // Contributed by adityasha4x71 using System; using System.Linq; class Program { static bool IsPalindrome(string word) { return word.SequenceEqual(word.Reverse()); } static string LargestPalin(string s) { // Convert string to array of words var words = s.Split( new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries); // Using LINQ to filter palindrome words var palindromeWords = words.Where(IsPalindrome); // Using LINQ to find the word with the maximum // length var largestPalindrome = palindromeWords .OrderByDescending(word = > word.Length) .FirstOrDefault(); return largestPalindrome; } static void Main(string[] args) { string s = "My name is ava and i love Geeksforgeeks"; string largestPalindrome = LargestPalin(s); Console.WriteLine(largestPalindrome); } } Time complexity:O(n)
Auxiliary Space:O(n)
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