Find Last Palindrome String in the given Array
Last Updated :
19 Jan, 2022
Given an array of strings arr[] of size N where each string consists only of lowercase English letter. The task is to return the last palindromic string in the array.
Note: It guarantees that always one palindromic string is present.
Examples:
Input: arr[] = {"abc", "car", "ada", "racecar", "cool"}
Output: "racecar"
Explanation: The Last string that is palindromic is "racecar".
Note that "ada" is also palindromic, but it is not the Last.
Input: arr[] = {"def", "aba"}
Output: "aba"
Approach: The solution is based on greedy approach. Check every string of an array from last if it is palindrome or not and also keep track of the last palindrome string. Follow the steps below to solve the problem:
- Initialize a string variable ans as an empty string.
- Iterate over the range (N, 0] using the variable i and perform the following tasks:
- If arr[i] is a palindrome, then set the value of ans as arr[i].
- After performing the above steps, print the value of ans as the answer.
Below is the implementation of the above approach:
C++
// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
// Function to check if given string
// is Palindrome or not
bool isPalindrome(string& s)
{
// Copy string s char into string a
string a = s;
reverse(s.begin(), s.end());
// Check if two string are equal or not
return s == a;
}
// Function to return last Palindrome string
string LastPalindrome(string arr[], int N)
{
// Loop to find the last palindrome string
for (int i = N - 1; i >= 0; i--) {
// Checking if given string is
// palindrome or not
if (isPalindrome(arr[i])) {
// Return the answer
return arr[i];
}
}
}
// Driver Code
int main()
{
string arr[]
= { "abc", "car", "ada", "racecar",
"cool" };
int N = sizeof(arr) / sizeof(arr[0]);
// Print required answer
cout << LastPalindrome(arr, N);
return 0;
}
// Java program for the above approach
class GFG {
// Function to check if given string
// is Palindrome or not
static boolean isPalindrome(String s)
{
// Copy string s char into string a
String a = s;
a = new StringBuffer(a).reverse().toString();
// Check if two string are equal or not
return s.equals(a);
}
// Function to return last Palindrome string
static String LastPalindrome(String arr[], int N) {
// Loop to find the last palindrome string
for (int i = N - 1; i >= 0; i--) {
// Checking if given string is
// palindrome or not
if (isPalindrome(arr[i])) {
// Return the answer
return arr[i];
}
}
return "Hi";
}
// Driver Code
public static void main(String args[]) {
String arr[] = { "abc", "car", "ada", "racecar", "cool" };
int N = arr.length;
// Print required answer
System.out.println(LastPalindrome(arr, N));
}
}
// This code is contributed by saurabh_jaiswal.
# Python code for the above approach
# Function to check if given string
# is Palindrome or not
def isPalindrome(s):
# find the length of a string
_len = len(s)
for i in range(_len // 2):
# check if first and last string are same
if s[i] != s[_len - 1 - i]:
return 0
return 1
# Function to return last Palindrome string
def LastPalindrome(arr, N):
# Loop to find the last palindrome string
for i in range(N - 1, 0, -1):
# Checking if given string is
# palindrome or not
if isPalindrome(arr[i]):
# Return the answer
return arr[i]
# Driver Code
arr = ["abc", "car", "ada", "racecar", "cool"]
N = len(arr)
# Print required answer
print(LastPalindrome(arr, N))
# This code is contributed by gfgking
// C# program for the above approach
using System;
class GFG {
// Function to check if given string
// is Palindrome or not
static bool isPalindrome(string s)
{
// Copy string s char into string a
char[] a = s.ToCharArray();
Array.Reverse(a);
string p = new string(a);
//a = new StringBuffer(a).reverse().toString();
// Check if two string are equal or not
return s.Equals(p);
}
// Function to return last Palindrome string
static string LastPalindrome(string[] arr, int N) {
// Loop to find the last palindrome string
for (int i = N - 1; i >= 0; i--) {
// Checking if given string is
// palindrome or not
if (isPalindrome(arr[i])) {
// Return the answer
return arr[i];
}
}
return "Hi";
}
// Driver Code
public static void Main() {
string []arr = { "abc", "car", "ada", "racecar", "cool" };
int N = arr.Length;
// Print required answer
Console.Write(LastPalindrome(arr, N));
}
}
// This code is contributed by ukasp.
<script>
// JavaScript code for the above approach
// Function to check if given string
// is Palindrome or not
function isPalindrome(s)
{
// find the length of a string
let len = s.length;
for (let i = 0; i < len / 2; i++)
{
// check if first and last string are same
if (s[i] !== s[len - 1 - i]) {
return 0;
}
}
return 1;
}
// Function to return last Palindrome string
function LastPalindrome(arr, N) {
// Loop to find the last palindrome string
for (let i = N - 1; i >= 0; i--) {
// Checking if given string is
// palindrome or not
if (isPalindrome(arr[i])) {
// Return the answer
return arr[i];
}
}
}
// Driver Code
let arr = ["abc", "car", "ada", "racecar",
"cool"];
let N = arr.length;
// Print required answer
document.write(LastPalindrome(arr, N));
// This code is contributed by Potta Lokesh
</script>
Time Complexity: O(N*W) where W is the maximum size of any string in arr[]
Auxiliary Space: O(1)
Similar Reads
Find all Palindrome Strings in given Array of strings Given an array of strings arr[] of size N where each string consists only of lowercase English letter. The task is to find all palindromic string in the array. Print -1 if no palindrome is present in the given array. Examples: Input: arr[] = {"abc", "car", "ada", "racecar", "cool"}Output: "ada", "ra
6 min read
Count of Palindrome Strings in given Array of strings Given an array of strings arr[] of size N where each string consists only of lowercase English letter. The task is to return the count of all palindromic string in the array. Examples: Input: arr[] = {"abc","car","ada","racecar","cool"}Output: 2Explanation: "ada" and "racecar" are the two palindrome
5 min read
Given a number, find the next smallest palindrome Given a number, in the form of an array num[] of size n containing digits from 1 to 9(inclusive). The task is to find the next smallest palindrome strictly larger than the given number.Examples:Input: num[] = [9, 4, 1, 8, 7, 9, 7, 8, 3, 2, 2]Output: [9, 4, 1, 8, 8, 0, 8, 8, 1, 4, 9]Explanation: Next
15+ min read
Palindrome pair in an array of words (or strings) Given an array of strings arr[] of size n, the task is to find if there exists two strings arr[i] and arr[j] such that arr[i]+arr[j] is a palindrome i.e the concatenation of string arr[i] and arr[j] results into a palindrome.Examples:Â Input: arr[] = ["geekf", "geeks", "or", "keeg", "abc", "bc"]Outpu
15+ min read
Count All Palindromic Subsequence in a given String Given a string s of length n, the task is to count number of palindromic subsequence (need not necessarily be distinct) present in the string s.Example: Input: s = "abcd"Output: 4Explanation: Palindromic subsequence are : "a" ,"b", "c" ,"d"Input: s = "aab"Output: 4Explanation: palindromic subsequenc
15+ min read