125. Valid Palindrome.cpp

/*
    written by Pankaj Kumar.
    country:-INDIA
*/
typedef long long ll ;


/* ascii value
A=65,Z=90,a=97,z=122
*/

/*  --------------------MAIN PROGRAM----------------------------*/
// to run ctrl+b
const ll INF=1e18;
const ll mod1=1e9+7;
const ll mod2=998244353;
// Techniques :
// divide into cases, brute force, pattern finding
// sort, greedy, binary search, two pointer
// transform into graph

// Experience :
// Cp is nothing but only observation and mathematics.


//Add main code here

class Solution
{
public:
    bool isPalindrome(string s)
    {
        string finalString="";
        for(auto x:s)
        {
            if((x>='a'&&x<='z')||(x>='A'&&x<='Z')||(x>='0'&&x<='9'))
            {
                if(x>='A'&&x<='Z')
                    x+=32;
                finalString+=x;
            }
        }
        s=finalString;
        reverse(finalString.begin(),finalString.end());
        
        if(finalString==s)
            return true;
        else
            return false;
    }
};

/* -----------------END OF PROGRAM --------------------*/
/*
* stuff you should look before submission
* constraint and time limit
* int overflow
* special test case (n=0||n=1||n=2)
* don't get stuck on one approach if you get wrong answer
*/