Codeforces 236A Boy or Girl Solution & Explanation

Difficulty : 800

Problem Description

Those days, many boys use beautiful girls’ photos as avatars in forums. So it is pretty hard to tell the gender of a user at the first glance. Last year, our hero went to a forum and had a nice chat with a beauty (he thought so). After that they talked very often and eventually they became a couple in the network.

But yesterday, he came to see “her” in the real world and found out “she” is actually a very strong man! Our hero is very sad and he is too tired to love again now. So he came up with a way to recognize users’ genders by their user names.

This is his method: if the number of distinct characters in one’s user name is odd, then he is a male, otherwise she is a female. You are given the string that denotes the user name, please help our hero to determine the gender of this user by his method.

Input

The first line contains a non-empty string, that contains only lowercase English letters — the user name. This string contains at most 100 letters.

Output

If it is a female by our hero’s method, print “CHAT WITH HER!” (without the quotes), otherwise, print “IGNORE HIM!” (without the quotes).

Examples

Note

For the first example. There are 6 distinct characters in “wjmzbmr”. These characters are: “w”, “j”, “m”, “z”, “b”, “r”. So wjmzbmr is a female and you should print “CHAT WITH HER!”.

Understand this problem in 3 seconds:

Given a string, check the number of its distinct characters. If the count is even, print ‘CHAT WITH HER!’; otherwise, print ‘IGNORE HIM!’.

Solution

In our first solution, we use HashSet to store the distinct characters and easily check their count.

C# Solution

Solution1 – HashSet

string username = Console.ReadLine();
HashSet<char> hSet = new HashSet<char>();

char[] charArr = username.ToCharArray();

foreach (char c in charArr)
{
    hSet.Add(c);
}

string res = hSet.Count%2==0? "CHAT WITH HER!" : "IGNORE HIM!";

Console.WriteLine(res);

Solution2 – LINQ Distinct

string username = Console.ReadLine();

int cnt = username.Distinct().Count();

string res = cnt%2==0? "CHAT WITH HER!" : "IGNORE HIM!";

Console.WriteLine(res);

A more easy way is to use LINQ built-in function distinct.

Java Solution

Solution1

import java.util.HashSet;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String username = scanner.nextLine();
        HashSet<Character> hSet = new HashSet<>();

        char[] charArr = username.toCharArray();

        for (char c : charArr) {
            hSet.add(c);
        }

        String res = hSet.size() % 2 == 0 ? "CHAT WITH HER!" : "IGNORE HIM!";
        System.out.println(res);
    }
}

Solution2 – streaming

import java.util.Scanner;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String username = scanner.nextLine();
        long cnt = username.chars()
                .mapToObj(c -> (char) c)
                .distinct()
                .count();

        String res = cnt % 2 == 0 ? "CHAT WITH HER!" : "IGNORE HIM!";
        System.out.println(res);
    }
}

Similar as C#’s LINQ, Java can use it’s own streaming to distinct and count easily

Python3 Solution

username = input()
s = set()

for u in username:
    s.add(u)
    
res = "CHAT WITH HER!" if len(s)%2==0  else "IGNORE HIM!"
print(res);

JavaScript Solution

username = readline();

var s = new Set();
for(var u of username){
    s.add(u);
}

var res = s.size % 2 === 0 ? "CHAT WITH HER!" : "IGNORE HIM!";
print(res);

Conclusion

Believe me, don’t trust this weird way to guess the gender of anyone !

🧡If my solution helps, that is my honor!

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✅If you got any problem about the explanation or you need other programming language solution, please feel free to let me know !!

The problem link : Problem – 236A – Codeforces

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