Given a string S representing a sentence, the task is to reverse the order of all palindromic words present in the sentence.
Examples:
Input: S = “mom and dad went to eye hospital”
Output: eye and dad went to mom hospital
Explanation: All palindromic words present in the string are “mom”, “dad” and “eye“, in the order of their occurrence. Reversing the order of their occurrence generates the sequence {“eye”, “dad”, “mom”}. Therefore, the modified string is “eye and dad went to mom hospital”.Input : S = “wow it is next level”
Output: level it is next wow.
Approach: Follow the steps below to solve the problem:
- Iterate over the characters of the string S and split the space-separated words from the sentence using split() and store them in a list, say lis.
- Append all the palindromic words to a new list, say newlist, using append() function.
- Reverse this new list using reverse() function.
- Traverse the list lis and keep replacing the palindromic words with the newlist[i] ( initially, i=0 ) and increment i by 1.
- Print the modified sentence
Below is the implementation of the above approach:
Java
// Java implementation of// the above approachimport java.util.*;class GFG{ // Function to check if a// string S is a palindromestatic boolean palindrome(String str){ int st = 0; int ed = str.length() - 1; while (st < ed) { if (str.charAt(st) == str.charAt(ed)) { st++; ed--; } else return false; } return true;}// Function to print the modified string// after reversing the order of occurrences// of all palindromic words in the sentencestatic void printReverse(String sentence){ // Stores the palindromic words ArrayList<String> newlist = new ArrayList<String>(); ArrayList<String> lis = new ArrayList<String>(); // Stores the words in the list String temp = ""; for(char x: sentence.toCharArray()) { if (x == ' ') { lis.add(temp); temp = ""; } else temp += x; } lis.add(temp); // Traversing the list for(String x: lis) { // If current word is a palindrome if (palindrome(x)) // Update newlist newlist.add(x); } // Reverse the newlist Collections.reverse(newlist); int j = 0; // Traverse the list for(int i = 0; i < lis.size(); i++) { // If current word is a palindrome if (palindrome(lis.get(i))) { // Update lis[i] lis.set(i,newlist.get(j)); // Increment j j = j + 1; } } // Print the updated sentence for(String x : lis) System.out.print(x + " ");}// Driver codepublic static void main(String[] args){ String sentence = "mom and dad went to eye hospital"; printReverse(sentence);}}// This code is contributed by offbeat |
Python3
# Python implementation of# the above approach# Function to check if a # string S is a palindromedef palindrome(string): if(string == string[::-1]): return True else: return False# Function to print the modified string# after reversing the order of occurrences# of all palindromic words in the sentencedef printReverse(sentence): # Stores the palindromic words newlist = [] # Stores the words in the list lis = list(sentence.split()) # Traversing the list for i in lis: # If current word is a palindrome if(palindrome(i)): # Update newlist newlist.append(i) # Reverse the newlist newlist.reverse() j = 0 # Traverse the list for i in range(len(lis)): # If current word is a palindrome if(palindrome(lis[i])): # Update lis[i] lis[i] = newlist[j] # Increment j j = j + 1 # Print the updated sentence for i in lis: print(i, end =" ")# Driver Codesentence = "mom and dad went to eye hospital"printReverse(sentence) |
C#
// C# implementation of// the above approachusing System;using System.Collections.Generic;class GFG{// Function to check if a// string S is a palindromestatic bool palindrome(string str){ int st = 0; int ed = str.Length - 1; while (st < ed) { if (str[st] == str[ed]) { st++; ed--; } else return false; } return true;}// Function to print the modified string// after reversing the order of occurrences// of all palindromic words in the sentencestatic void printReverse(string sentence){ // Stores the palindromic words List<string> newlist = new List<string>(); List<string> lis = new List<string>(); // Stores the words in the list string temp = ""; foreach(char x in sentence) { if (x == ' ') { lis.Add(temp); temp = ""; } else temp += x; } lis.Add(temp); // Traversing the list foreach(string x in lis) { // If current word is a palindrome if (palindrome(x)) // Update newlist newlist.Add(x); } // Reverse the newlist newlist.Reverse(); int j = 0; // Traverse the list for(int i = 0; i < lis.Count; i++) { // If current word is a palindrome if (palindrome(lis[i])) { // Update lis[i] lis[i] = newlist[j]; // Increment j j = j + 1; } } // Print the updated sentence foreach(string x in lis) Console.Write(x + " ");}// Driver Codepublic static void Main(){ string sentence = "mom and dad went to eye hospital"; printReverse(sentence);}}// This code is contributed by ukasp |
Javascript
<script>// Javascript implementation of// the above approach// Function to check if a // string S is a palindromefunction palindrome(str){ var st = 0; var ed = str.length - 1; while (st < ed) { if (str[st] == str[ed]) { st++; ed--; } else return false; } return true;}// Function to print the modified string// after reversing the order of occurrences// of all palindromic words in the sentencefunction printReverse(sentence){ // Stores the palindromic words var newlist = []; var lis = []; // Stores the words in the list var temp = ""; for(var i =0; i<sentence.length;i++) { if (sentence[i] == ' ') { lis.push(temp); temp = ""; } else temp += sentence[i]; } lis.push(temp); // Traversing the list for(var i =0; i<lis.length;i++) { // If current word is a palindrome if (palindrome(lis[i])) // Update newlist newlist.push(lis[i]); } // Reverse the newlist newlist.reverse(); var j = 0; // Traverse the list for(var i = 0; i < lis.length; i++) { // If current word is a palindrome if (palindrome(lis[i])) { // Update lis[i] lis[i] = newlist[j]; // Increment j j = j + 1; } } // Print the updated sentence for(var i = 0; i < lis.length; i++) { document.write( lis[i] + " "); }}// Driver Codevar sentence = "mom and dad went to eye hospital";printReverse(sentence);</script> |
C++
// C++ implementation of the above approach#include <iostream>#include <vector>#include <algorithm>using namespace std;// Function to check if a// string S is a palindromebool palindrome(string str){ int st = 0; int ed = str.length() - 1; while (st < ed) { if (str[st] == str[ed]) { st++; ed--; } else return false; } return true;}// Function to print the modified string// after reversing the order of occurrences// of all palindromic words in the sentencevoid printReverse(string sentence){ // Stores the palindromic words vector<string> newlist; vector<string> lis; // Stores the words in the list string temp = ""; for(char x: sentence) { if (x == ' ') { lis.push_back(temp); temp = ""; } else temp += x; } lis.push_back(temp); // Traversing the list for(string x: lis) { // If current word is a palindrome if (palindrome(x)) // Update newlist newlist.push_back(x); } // Reverse the newlist reverse(newlist.begin(), newlist.end()); int j = 0; // Traverse the list for(int i = 0; i < lis.size(); i++) { // If current word is a palindrome if (palindrome(lis[i])) { // Update lis[i] lis[i] = newlist[j]; // Increment j j = j + 1; } } // Print the updated sentence for(string x : lis) cout << x << " ";}// Driver codeint main(){ string sentence = "mom and dad went to eye hospital"; printReverse(sentence); return 0;}// Contributed by adityashae15 |
Output:
eye and dad went to mom hospital
Time Complexity: O(N)
Auxiliary Space: O(N) because it is using extra space for list newlist and lis
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