/*
C++ Palindrome Checker program by lolman_ks.
Checks palindromic string WITHOUT reversing it.
Same logic can be used to build this program in other languages.
*/
/*
Logic: In a palindromic string, the 1st and last, 2nd and 2nd last, and so
on characters are equal.
Return false from the function if any of these matches, i.e (1st and last),
(2nd and 2nd last) are not equal.
*/
#include <iostream>
using namespace std;
bool checkPalindromicString(string text){
int counter_1 = 0; //Place one counter at the start.
int counter_2 = text.length() - 1; //And the other at the end.
//Run a loop till counter_2 is not less that counter_1.
while(counter_2 >= counter_1){
if(text[counter_1] != text[counter_2]) return false; //Check for match.
//Note: Execution of a function is halted as soon as a value is returned.
else{
++counter_1; //Move the first counter one place ahead.
--counter_2; //Move the second character one place back.
}
}
return true;
/*
Return true if the loop is not broken because of unequal characters and it
runs till the end.
If the loop runs till the condition specified in it, i.e
(counter_2 >= counter1), that means all matches are equal and the string is
palindromic.
*/
}
//Implementation of the function.
int main(){
cout << checkPalindromicString("racecar") << endl; //Outputs 1 (true).
cout << checkPalindromicString("text") << endl; //Outputs 0 (False).
if(checkPalindromicString("lol")){
cout << "#lolman_ks";
}
//Outputs #lolman_ks.
return 0;
}
//I hope this would be useful to you all, please promote this answer if it is.
//#lolman_ks
function palindrome(str) {
var re = /[W_]/g;// representing Non-alphanumetic characters
var lowRegStr = str.toLowerCase().replace(re, '');
var reverseStr = lowRegStr.split('').reverse().join('');
return reverseStr === lowRegStr;
}
palindrome("A man, a plan, a canal. Panama");
let data = 12421
const dataOne = data.toString().split("").reverse().join("");
data = data.toString();
dataOne === data ? console.log("Palindrom")
: console.log("Not Palindorm");
// The Setup
function palindrome(str) {
// Using Regex to remove all the special character, converted all the string to lowercase to ease working with and assign it to a new variable
let newStr = str.replace(/[^a-zA-Z0-9]/g, '').toLowerCase();
// Split the string, reverse, join then assign it to a new variable
let revStr = newStr.split('').reverse().join('');
// return their value
return newStr === revStr;
}
palindrome("A man, a plan, a canal. Panama");
var isPalindrome = function(x) {
let y = x
let r = y.toString().split('').reverse().join('')
let t = Number(r)
if(t ===x){
return true
}
else{
return false}
}
<script>
// function that check str is palindrome or not
function check_palindrome( str )
{
let j = str.length -1;
for( let i = 0 ; i < j/2 ;i++)
{
let x = str[i] ;//forward character
let y = str[j-i];//backward character
if( x != y)
{
// return false if string not match
return false;
}
}
/// return true if string is palindrome
return true;
}
//function that print output is string is palindrome
function is_palindrome( str )
{
// variable that is true if string is palindrome
let ans = check_palindrome(str);
//condition checking ans is true or not
if( ans == true )
{
console.log("passed string is palindrome ");
}
else
{
console.log("passed string not a palindrome");
}
}
// test variable
let test = "racecar";
is_palindrome(test);
</script>
int main()
{
char str1[20], str2[20];
int i, j, len = 0, flag = 0;
cout << "Enter the string : ";
gets(str1);
len = strlen(str1) - 1;
for (i = len, j = 0; i >= 0 ; i--, j++)
str2[j] = str1[i];
if (strcmp(str1, str2))
flag = 1;
if (flag == 1)
cout << str1 << " is not a palindrome";
else
cout << str1 << " is a palindrome";
return 0;
}
class Solution :
def isPalindrome(self, string: str ) :
'''
A function to check if a string is Palindrome or not!
:param string: string to be checked
:return: True if it is palindrome else False
'''
string = string.lower()
s_stripped = ''.join(list( filter ( lambda x : x.isalnum () == True , string)))
return s_stripped == s_stripped[::-1]
if __name__ == '__main__' :
string = 'Was it a car or a cat I saw!!'
print (f'Is "{string}" a palindrome? : {Solution ().isPalindrome (string)}')
string2 = 'A man, a plan,'
print (f'Is "{string2}" a palindrome? : {Solution ().isPalindrome (string2)}')
int main()
{
char str1[20], str2[20];
int i, j, len = 0, flag = 0;
cout << "Enter the string : ";
gets(str1);
len = strlen(str1) - 1;
for (i = len, j = 0; i >= 0 ; i--, j++)
str2[j] = str1[i];
if (strcmp(str1, str2))
flag = 1;
if (flag == 1)
cout << str1 << " is not a palindrome";
else
cout << str1 << " is a palindrome";
return 0;
}
#include <iostream>
#include <deque>
bool is_palindrome(const std::string &s){
if(s.size() == 1 ) return true;
std::deque<char> d ;
for(char i : s){
if(std::isalpha(i)){
d.emplace_back( toupper(i) );
}
}
auto front = d.begin();
auto back = d.rbegin();
while( (front != d.end()) || (back != d.rend())){
bool ans = (*front == *back);
if(!ans){
return ans;
}
++front;++back;
}
return true;
}
int main() {
std::string s = "A man, a plan, a cat, a ham, a yak, a yam, a hat, a canal-Panama!";
std::cout << std::boolalpha << is_palindrome(s) << std::endl;
return 0;
}
// can we generate palindrome string by suffling
// the character of the string s
public bool CanBePalindrome(string s)
{
var dict = new Dictionary<char, int>();
for (int j =0; j < s.Length; j++)
{
var item = s[j];
if (dict.ContainsKey(item))
{
dict[item]++;
if (dict[item] == 2)
{
dict.Remove(item);
}
}
else
{
dict.Add(item, 1);
}
}
return dict.Count <= 1;
}