Question

1. A palindrome is a string that reads the same forward and backward, for examples, redivider, deified, civic, radar, racecar, redder.

Write a short program( in C++) that is the most efficient you can think of for determining whether an input string of n characters is a palindrome.

Answer 1

#include <iostream>
#include <string>

using namespace std;

bool isPalindrome(string);

int main() {
    cout << "Enter a string: ";
    string s;
    cin >> s;
    if (isPalindrome(s)) {   // check if it's a palindrome
        cout << s << " is a palindrome" << endl;
    } else {
        cout << s << " is not a palindrome" << endl;
    }
    return 0;
}

bool isPalindrome(string s) {
    for (int i = 0; i < s.length(); ++i) {   // go through all characters
        if (s[i] != s[s.length() - i - 1]) { // if characters from beginning is not same as character from end
            return false;   // then, return false
        }
    }
    return true;    // if it's a palindrome then return true
}