Palindromic String | Basics of Input/Output

Problem Statement : 

You have been given a String S. You need to find and print whether this string is a palindrome or not. If yes, print "YES" (without quotes), else print "NO" (without quotes).

Problem Link: 

https://www.hackerearth.com/practice/basic-programming/input-output/basics-of-input-output/practice-problems/algorithm/palindrome-check-2/

Input Format : 
The first and only line of input contains the String S. The String shall consist of lowercase English alphabets only.

Output Format :
Print the required answer on a single line.

Constraints : 

 $1\le |S|\le 100$

String S consists of lowercase English Alphabets only.

Solution : 

//Code here

#include <iostream>

using namespace std;

int main()

{

char str[100];    

cin>>str;         // input string

int i,j;        // looping variables

int len;       // to store string length

for(len=0;str[len]!='\0';len++);  // counting string length

int flag=1;  // flag variable

for(i=0,j=len-1;i<len/2;i++,j--)

{

    if(str[i]!=str[j])  // if adjacent characters are not same

    {

        flag=0; break; //string not palindrome, flag 0, break loop

    }

}

if(flag==1)

  cout<<"YES";

else

  cout<<"NO";

  

return 0;

}

Code Snippet

Submission

Solution Explained : 

We used a character array str of size 100 ( as max size of string is 100 ). Then we declare two looping variables i and j. We used a integer len to store length of string str. We used a loop of len from len=0 to str[len]!='/0' to count the length of string str ( Line No.13). Then we started a loop of i and j, i pointing to 1st character and j pointing to last character, for each iteration we checked if characters pointed by i-j are same or not, if same we i++ and j--. Likewise we compare all the adjacent characters of string str. If at any instance adjacent characters are not same, we make flag=0 and break the loop. Finally we check for the value of flag, if it is 1 i.e., unchanged it implies all adjacent characters are same and string is Palindrome, if value of flag is other, that means string is not Palindrome.

This completes our Program.

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Rahul Badgujar

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