7. 회문 문자열

import java.util.*;

class Main {
	public String solution(String str) {
		String answer = "YES";
		str = str.toUpperCase();
		int lt = 0, rt = str.length() - 1;

		while (lt < rt) {
			if (str.charAt(lt) != str.charAt(rt)) {
				answer = "NO";
				break;
			} else {
				lt++;
				rt--;
			}
		}
		return answer;
	}

	public static void main(String[] args) {
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		System.out.println(T.solution(kb.nextLine()));
	}
}

 

import java.util.*;

class Main {
	public String solution(String str) {
		String answer = "YES";
		str = str.toUpperCase();		
		for(int i=0; i < str.length()/2; i++) {
			if(str.charAt(i) != str.charAt(str.length()-1-i)) {
				answer ="NO";
				break;
			}
		}
		return answer;
	}

	public static void main(String[] args) {
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		System.out.println(T.solution(kb.nextLine()));
	}
}

 

 

import java.util.*;

class Main {
	public String solution(String str) {
		String answer = "YES";
		String rev = new StringBuilder(str).reverse().toString();

		if (!str.equalsIgnoreCase(rev))
			return "NO";

		return answer;
	}

	public static void main(String[] args) {
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		System.out.println(T.solution(kb.nextLine()));
	}
}

str.equalsIgnoreCase() //대소문자무시비교