Write a program to check if a sentence is a palindrome or not. You can ignore white spaces and other characters to consider sentences as a palindrome.
Examples:
Input : str = "Too hot to hoot." Output : Sentence is palindrome. Input : str = "Abc def ghi jklm." Output : Sentence is not palindrome.
Note: There may be multiple spaces and/or dots between two words.
Method#1: To find if a sentence is palindrome, compare each character from left and right. If they are equal, compare until left and right of string are equal or right becomes less than left. Remember to ignore white spaces and other characters in a string.
Implementation:
// CPP program to find if a sentence is // palindrome #include <bits/stdc++.h> using namespace std;
// To check sentence is palindrome or not bool sentencePalindrome(string str)
{ int l = 0, h = str.length() - 1;
// Lowercase string
for ( int i = 0; i <= h; i++)
str[i] = tolower (str[i]);
// Compares character until they are equal
while (l <= h) {
// If there is another symbol in left
// of sentence
if (!(str[l] >= 'a' && str[l] <= 'z' ))
l++;
// If there is another symbol in right
// of sentence
else if (!(str[h] >= 'a' && str[h] <= 'z' ))
h--;
// If characters are equal
else if (str[l] == str[h])
l++, h--;
// If characters are not equal then
// sentence is not palindrome
else
return false ;
}
// Returns true if sentence is palindrome
return true ;
} // Driver program to test sentencePalindrome() int main()
{ string str = "Too hot to hoot." ;
if (sentencePalindrome(str))
cout << "Sentence is palindrome." ;
else
cout << "Sentence is not palindrome." ;
return 0;
} |
// Java program to find if a sentence is // palindrome public class GFG
{ // To check sentence is palindrome or not
static boolean sentencePalindrome(String str)
{
int l = 0 ;
int h = str.length()- 1 ;
// Lowercase string
str = str.toLowerCase();
// Compares character until they are equal
while (l <= h)
{
char getAtl = str.charAt(l);
char getAth = str.charAt(h);
// If there is another symbol in left
// of sentence
if (!(getAtl >= 'a' && getAtl <= 'z' ))
l++;
// If there is another symbol in right
// of sentence
else if (!(getAth >= 'a' && getAth <= 'z' ))
h--;
// If characters are equal
else if ( getAtl == getAth)
{
l++;
h--;
}
// If characters are not equal then
// sentence is not palindrome
else return false ;
}
// Returns true if sentence is palindrome
return true ;
}
// Driver program to test sentencePallindrome()
public static void main(String[] args)
{
String str = "Too hot to hoot." ;
if ( sentencePalindrome(str))
System.out.println( "Sentence is palindrome" );
else
System.out.println( "Sentence is not" + " " +
"palindrome" );
}
} //This code is contributed by Sumit Ghosh |
# Python program to find if a sentence is palindrome # To check sentence is palindrome or not def sentencePalindrome(s):
l, h = 0 , len (s) - 1
# Lowercase string
s = s.lower()
# Compares character until they are equal
while (l < = h):
# If there is another symbol in left
# of sentence
if ( not (s[l] > = 'a' and s[l] < = 'z' )):
l + = 1
# If there is another symbol in right
# of sentence
elif ( not (s[h] > = 'a' and s[h] < = 'z' )):
h - = 1
# If characters are equal
elif (s[l] = = s[h]):
l + = 1
h - = 1
# If characters are not equal then
# sentence is not palindrome
else :
return False
# Returns true if sentence is palindrome
return True
# Driver program to test sentencePalindrome() s = "Too hot to hoot."
if (sentencePalindrome(s)):
print ( "Sentence is palindrome." )
else :
print ( "Sentence is not palindrome." )
|
// C# program to find if a // sentence is palindrome using System;
public class GFG
{ // To check sentence is
// palindrome or not
static bool sentencePalindrome(String str)
{
int l = 0;
int h = str.Length - 1;
// Lowercase string
str = str.ToLower();
// Compares character until
// they are equal
while (l <= h)
{
char getAtl = str[l];
char getAth = str[h];
// If there is another symbol
// in left of sentence
if (!(getAtl >= 'a' &&
getAtl <= 'z' ))
l++;
// If there is another symbol
// in right of sentence
else if (! (getAth >= 'a' &&
getAth <= 'z' ))
h--;
// If characters are equal
else if ( getAtl == getAth)
{
l++;
h--;
}
// If characters are not equal then
// sentence is not palindrome
else
return false ;
}
// Returns true if sentence
// is palindrome
return true ;
}
// Driver Code
public static void Main()
{
String str = "Too hot to hoot." ;
if ( sentencePalindrome(str))
Console.Write( "Sentence is palindrome" );
else
Console.Write( "Sentence is not" + " " +
"palindrome" );
}
} // This code is contributed by Nitin Mittal. |
<?php // PHP program to find if a sentence is // palindrome // To check sentence is palindrome or not function sentencePalindrome( $str )
{ $l = 0;
$h = strlen ( $str )-1;
// Lowercase string
for ( $i = 0; $i < $h ; $i ++)
$str [ $i ] = strtolower ( $str [ $i ]);
// Compares character until they are equal
while ( $l <= $h ) {
// If there is another symbol in left
// of sentence
if (!( $str [ $l ] >= 'a' && $str [ $l ] <= 'z' ))
$l ++;
// If there is another symbol in right
// of sentence
else if (!( $str [ $h ] >= 'a' && $str [ $h ] <= 'z' ))
$h --;
// If characters are equal
else if ( $str [ $l ] == $str [ $h ])
{
$l ++;
$h --;
}
// If characters are not equal then
// sentence is not palindrome
else
return false;
}
// Returns true if sentence is palindrome
return true;
} // Driver program to test sentencePalindrome() $str = "Too hot to hoot." ;
if (sentencePalindrome( $str ))
echo "Sentence is palindrome." ;
else echo "Sentence is not palindrome." ;
return 0;
?> |
<script> // Javascript program to find if a sentence is // palindrome // To check sentence is palindrome or not
function sentencePalindrome(str)
{
let l = 0;
let h = str.length-1;
// Lowercase string
str = str.toLowerCase();
// Compares character until they are equal
while (l <= h)
{
let getAtl = str[l];
let getAth = str[h];
// If there is another symbol in left
// of sentence
if (!(getAtl >= 'a' && getAtl <= 'z' ))
l++;
// If there is another symbol in right
// of sentence
else if (!(getAth >= 'a' && getAth <= 'z' ))
h--;
// If characters are equal
else if ( getAtl == getAth)
{
l++;
h--;
}
// If characters are not equal then
// sentence is not palindrome
else
return false ;
}
// Returns true if sentence is palindrome
return true ;
}
// Driver program to test sentencePallindrome()
let str = "Too hot to hoot." ;
if ( sentencePalindrome(str))
document.write( "Sentence is palindrome" );
else
document.write( "Sentence is not" + " " +
"palindrome" );
//This code is contributed by avanitrachhadiya2155
</script> |
Sentence is palindrome.
Time Complexity: O(N) where N is the length of the sentence
Space Complexity: O(1)
Method#2: String.erase(), reverse method simultaneously
Following are steps for our idea:
- When user input an sentence, it is further passed inside a method which will evaluate the result or the logic part.
- Method uses following logic for evaluating the result:
- It first convert all the latter in sentence to lowercase.
- It uses String.erase() method on sentence to erase the white-space in between the sentence.
- Now it uses the reverse method to reverse the sentence.
- It checked the sentence and reversed sentence and return result.
Below are implementation of above idea.
// CPP program to find if a sentence is // palindrome #include <bits/stdc++.h> using namespace std;
// To check sentence is palindrome or not bool isPalindrome(string str)
{ // Transforming to lowercase
transform(str.begin(), str.end(), str.begin(), :: tolower );
// Removing the white-spaces
str.erase( remove (str.begin(), str.end(), ' ' ), str.end());
// Creating the copy to string
string s1 = str;
string s2 = str;
// Reversing the string s1
reverse(s1.begin(), s1.end());
// Evaluating Result
return s1 == s2;
} // Driver program to test sentencePalindrome() int main()
{ string str = "Too hot to hoot" ;
if (isPalindrome(str))
cout << "Sentence is palindrome." ;
else
cout << "Sentence is not palindrome." ;
return 0;
} |
import java.io.*;
// Java program to find if a sentence is // palindrome public class GFG
{ // To check sentence is palindrome or not
static boolean sentencePalindrome(String s)
{
if (s.isEmpty()) // if String s is empty return true
return true ;
String str = s.toLowerCase(); // convert the whole string into lower case alphabet
//remove non-alphanumeric characters
// replace the given string with empty string except the pattern [^a-zA-Z0-9]
str = str.replaceAll( "[^a-zA-Z0-9]" , "" );
//The reverse() method of StringBuilder is used to reverse the characters in the StringBuilder.
StringBuilder revstr = new StringBuilder(str);
revstr.reverse();
String rstr = revstr.toString();
if (str.equals(rstr)) //if string and reversed string both are equal return true
return true ;
return false ; //else return false
} // Driver program to test sentencePallindrome()
public static void main(String[] args)
{
String str = "Too hot to hoot." ;
if ( sentencePalindrome(str))
System.out.println( "Sentence is palindrome" );
else
System.out.println( "Sentence is not" + " " +
"palindrome" );
}
} |
# Python program to find if a sentence is # palindrome # To check sentence is palindrome or not def isPalindrome(s):
# Replacing the white-space in string
s1 = s.replace( ' ' , '')
# converting string to lowercase
s1 = s1.lower()
# Reversing the string
s2 = s1[:: - 1 ];
# Evaluating the result
return True if s1 = = s2 else False # Driver program to test sentencePalindrome() s = "Too hot to hoot"
if (isPalindrome(s)):
print ( "Sentence is palindrome." )
else :
print ( "Sentence is not palindrome." )
# This code is contributed by Sachin Bisht |
using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
// C# program to find if a sentence is // palindrome class HelloWorld {
// To check sentence is palindrome or not
public static bool isPalindrome( string str)
{
// Removing the white-spaces
str = str.Replace( " " , string .Empty);
// Transforming to lowercase
str = str.ToLower();
// Creating the copy to string
string s1 = str;
string s2 = str;
// Reversing the string s1
char [] charArray = str.ToCharArray();
Array.Reverse(charArray);
s1 = new string (charArray);
// Evaluating Result
return s1 == s2;
}
static void Main() {
string str = "Too hot to hoot" ;
if (isPalindrome(str))
Console.WriteLine( "Sentence is palindrome." );
else
Console.WriteLine( "Sentence is not palindrome." );
}
} // The code is contributed by Nidhi goel. |
// Javascript program to find if a sentence is // palindrome // To check sentence is palindrome or not
function isPalindrome(str)
{
// Replacing the white-space
let s1 = str.split( ' ' ).join( '' );
// Converting string to lower-case
s1 = s1.toLowerCase();
// Reversing the string
let s2 = s1.split( '' ).reverse().join( '' );
// Evaluating the result
return true ? s1 == s2 : false ;
}
// Driver program to test sentencePallindrome()
let str = "Too hot to hoot" ;
if ( isPalindrome(str))
console.log( "Sentence is palindrome" );
else
console.log( "Sentence is not palindrome" );
//This code is contributed by avanitrachhadiya2155
|
Sentence is palindrome.
Time Complexity: O(N)
Space Complexity: O(N)
Method: #3: Using Stack
Here we are using the stack to reverse the array and then check whether the sentence is palindrome or not.
// C++ program for the above approach #include <iostream> #include <algorithm> #include <stack> using namespace std;
bool sentencePalindrome(string s)
{ string str = "" ;
for ( char c : s){
if ( isalnum (c))
str += tolower (c);
}
string reverse_str = str;
reverse(reverse_str.begin(), reverse_str.end());
return str == reverse_str;
} int main()
{ string str = "Too hot to hoot." ;
if (sentencePalindrome(str))
cout << "Sentence is palindrome\n" ;
else
cout << "Sentence is not palindrome\n" ;
return 0;
} // This code is contributed by adityashatmfh |
import java.io.*;
import java.util.*;
class GFG {
static boolean sentencePalindrome(String s)
{
char [] str = s.toCharArray();
Stack<Character> stack = new Stack<>();
for ( int i = 0 ; i < s.length(); i++){
if (Character.isLetterOrDigit(str[i]))
stack.push(str[i]);
}
String string = "" ;
String reverse = "" ;
for (Character character : stack) {
reverse += Character.toLowerCase(character);
}
while (!stack.isEmpty()){
string += Character.toLowerCase(stack.pop());
}
return string.equals(reverse);
}
public static void main(String[] args)
{
String str = "Too hot to hoot." ;
if ( sentencePalindrome(str))
System.out.println( "Sentence is palindrome" );
else
System.out.println( "Sentence is not" + " " +
"palindrome" );
}
} |
# Python program for the above approach def sentence_palindrome(s):
str_ = ""
for c in s:
if c.isalnum():
str_ + = c.lower()
reverse_str = str_[:: - 1 ]
return str_ = = reverse_str
if __name__ = = "__main__" :
str_ = "Too hot to hoot."
if sentence_palindrome(str_):
print ( "Sentence is palindrome" )
else :
print ( "Sentence is not palindrome" )
# This code is contributed by prince |
using System;
using System.Collections.Generic;
class GFG {
static bool sentencePalindrome( string s)
{
// Convert string to character array
char [] str = s.ToCharArray();
Stack< char > stack = new Stack< char >();
// Push only letters and digits onto the stack
for ( int i = 0; i < s.Length; i++){
if (Char.IsLetterOrDigit(str[i]))
stack.Push(str[i]);
}
string originalString = "" ;
string reverseString = "" ;
// Create a string from the characters in the stack
foreach ( char character in stack) {
reverseString += Char.ToLower(character);
}
// Pop characters from the stack to create a reversed string
while (stack.Count > 0){
originalString += Char.ToLower(stack.Pop());
}
// Compare the original and reversed strings
return originalString.Equals(reverseString);
}
public static void Main( string [] args)
{
string str = "Too hot to hoot." ;
if (sentencePalindrome(str))
Console.WriteLine( "Sentence is palindrome" );
else
Console.WriteLine( "Sentence is not" + " " +
"palindrome" );
}
} |
function sentencePalindrome(s) {
let str = "" ;
for (let i = 0; i < s.length; i++) {
const c = s.charAt(i);
if (c.match(/[a-zA-Z0-9]/))
str += c.toLowerCase();
}
const reverse_str = str.split( "" ).reverse().join( "" );
return str === reverse_str;
} const str = "Too hot to hoot." ;
if (sentencePalindrome(str))
console.log( "Sentence is palindrome" );
else console.log( "Sentence is not palindrome" );
|
Sentence is palindrome
Time Complexity: O(N)
Space Complexity: O(N)