Valid-palindrome.cpp

class Solution {
    public:
    bool valid(char ch){
         if ((ch>='a' && ch<='z')||(ch>='A' && ch<='Z')||(ch>='0' && ch<='9')){
            return 1;
    }
        return 0;
    }
    char lowercase(char ch){
        if((ch>='a' && ch<='z')||(ch>='0' && ch<='9'))
            return ch;
        else {
            char temp =ch-'A'+'a';
            return temp;
        }
    }
    
    bool checkpalindrome(string a){
    int s=0;
    int e=a.length()-1;
    while(s<=e){
        if(a[s]!=a[e]){
            return 0;
        }
        else {
            s++;
            e--;
        }
    }
        return 1;
    }
    bool isPalindrome(string s) {
        string temp ="";
        for(int j=0;j<=s.length();j++){
            if(valid(s[j])){
                temp.push_back(s[j]);
            }
        }
        for(int j=0;j<temp.length();j++){
            temp[j]=lowercase(temp[j]);
        }
        
        return checkpalindrome(temp);
        
    }
};